Times Cryptic 25751 Mystifying for Apes or a distinct feeling of déjà vu.

Last time I was here in the hot seat, Rev John Galbraith Graham, of blessed memory, appeared under his pen-name in a crossword that mirrored, to a degree, his looser and affable style, And lo! Two weeks to the day, here he is again, this time promoted to the very top of the grid from one line down. So no complaining about an obscure tree name this time, it’s definitely been here within living memory and only this of us with short term memory issues can have any kind of excuse. There is an obscure Burmese tribe to have a go at, but fortunately only as a bit of wordplay in a much more familiar river. There’s also a Victorian artist to drag from memory and/or make up from the wordplay. I can tell you he’s no J M W Turner or John Everett Millais, but I’m pretty sure I’ve seen his stuff, possibly on Christmas cards, or on countless “I don’t know much about art but I know what I like” drawing room walls.
I completed this thing in 18′ 19″, only 1.36 Gilhams, and I might have been even closer had I spelled the Mexican food with the right letter at the end making 27ac easy. Here’s how it all works

Across

1   ARAUCARIA  The monkey puzzle tree when it isn’t being Rev John. The weird mix of plants – carap is a sort of mahogany –
     unlikely to be seen together on any sane planet, signals that they are just there for the letters, in this case the middle
     triplets, which helpfully need no rearranging.
6   SCUFF  S(on) + CUFF gives you “scrape”. Expect to see this one soon in the Quickie
9   RADAR  Equipment is the rather generic definition. RADA is the Royal Academy of Dramatic Art (that genus of players).to
     which you add R(ight)
10 TOSCANINI  The Times has a relatively small pantheon of conductors, and this one appears when the setter needs 9
     letters ending I TOSCA the Puccini opera, IN for “popular” wrapped in, N(orthern) I(reland)
11 A MONTH OF SUNDAYS The proverbial unconscionably long period of time. I could’t read this as anything other than a
     cryptic definition
13 GRIMSHAW  John Atkinson of that ilk. If you run the name through a thesaurus, you might be lucky enough to get “black
     wood” from the two syllables. His pictures, all 200 of them, look like this:

14 ANGOLA The country. Place A LOG reversed after A N(ew)
16 NAUTCH Possibly an unfamiliar word to some, it just means “dance” in several North Indian languages, Wiki says, rather
     coyly “the Nautch girls performed Nautches for the pleasure of men.” Derive it from NUT – “fanatic” holding A and
    followed by the full range of taps, i.e. Hot and Cold. What, no mixer?
18 DICTATOR  I did not know the extraordinary Roman magistrate (verbatim from Chambers) definition, but the wordplay
    reverses ROT AT CID
21 POLITICAL ASYLUM  is precisely protection from harmful state, and CAPITALISM YOU’LL provides the necessary anagram
    fodder signalled by he need to reform.
23 APPALLING  “Very bad” given by P(age) ALL (entirely) wrapped in APING (copying)
25 AVAIL  On line, this clue has a tag after it, viz – bit fairer I think (5), which I would suggest is an undeleted comment from
    our esteemed editor: you see he does care about our well-being! The actual clue has “benefit” as the one-word
    definition,derived from TRAVAIL (labour) without T(ons) and R(ight)
26 KNOWN  A soundalike clue, slightly flawed, I think, as the 3 o’clock (ninth hour) church service is NONES and the S is not
     silent. Am I missing something?
27 MANDATORY  “Essential” is the adequate definition. Enclose DAT (shortened date) and O(ther) R(anks) “men” in MANY “lots”

Down

1   ATRIA   An atrium, of which this is the plural, is the central courtyard in a Roman house. A TRIAL is “terminated” with early
     implicit
2   AUDIOVISUAL  A rather gimme anagram, both in the odd looking fodder, I AVOID USUAL and the indicator “arrangement”
3   CARITAS  is one of the three Christian virtues, in Latin fides, spes, caritas, faith, hope and charity, more commonly
     translated these days as “love”. A shortened legal action, CAS(e) encloses the lovely RITA, meter maid
4   RATIONAL  Defined as “clearly thinking.”Of a whole age group” gives GENERATIONAL, remove the GEN (info – a neat
     abbreviation to match GENeral Information) and the E(cstasy)
5   ASSIST  Spot the Roman numerals in CLASSICIST and remove all but one of the I’s. Try not to remember that, in medieval
     Roman, S was 7 or 70, A was 50 or 500, and T was 160, or you won’t have anything to go into the grid.
6   SHANNON. The Shan are indigenous to adjacent parts of Burma, China, Laos and Thailand. If I knew this, I had forgotten,
     but I know the River Shannon well enough so the guess is a fairly confident one, given the NO N(ame) ending and the
     crossing letters. “River” must be separated from “people” before solving. Burma is currently Myanmar. It’ll never catch on.
7   UNI  The familiar abbreviation for a place of academic study, and the Student UNION without ON for “working”
8   FAIR’S FAIR   “Just” twice as given, with S(erve) in between. “Play the game as a parallel admonition. I say old chap.
12 AMONTILLADO  for those who like their sherry dry-ish. Slot the pieces together as given: AM ON (working, again) TILL
     (up to) A DO (party)
13 GANGPLANK  The Royal Yacht Britannia is currently parked in Edinburgh, so the clue has a certain appositeness. GANG is
     Scottish for go or proceed, scheme gives PLAN and add the K(ing) for the means of access
15 MILLIGAN  “I told you I was ill” Spike, original Goon. L(ogistics) in an anagram of MAILING
17 CATALAN Genitive of Catalonia formed from CAT(amaran) and our fellow, ALAN
19 TOSTADA  Why I originally put TOSTADO I can’t imagine. TOSA is the dog, TAD “a little”, the whole a Mexican word for
     toast, available in kit form from your local supermarket .
20 SCHISM  Hows your geology? SCHIST is the rock, knock off the T and replace it with M(ountain) for “rift” Most often in use
     to describe Church splits.when fides, spes, et caritas go out of the window
22 MOLLY  both the Malone who wheeled her wheelbarrow through Dublin selling seafood alive-o and a tropical fish
24 PRO  Take the M(inutes) away from a PROM(enade concert)