Monthly Club Special 20,258: Oh, The Cluemanity!

Some insane words and super duper cluing in this one. I really loved the next level deviousness of 6ac, all reverse cryptic and &lit stuff in general, and the great surface of 27ac: but my Clue of the Month is a coin flip between 22ac, just for managing to clue CI by reference to chess notation, and 5dn for discovering such an unlikely ancient word that turns out to be completely perfect for becoming a crossword clue.

My hat, as ever, is off. Thank you so much setter!

Definitions underlined, (ABC)* indicating anagram of ABC, {} deletions and [] other indicators.

Across
1 Compulsion to shift about — not that one should interrupt drivers (9)
ACATHISIA – CA [about] THIS [not that] I [one], “interrupting” A.A. (automobile association)
6 Channels turning orange, then later fluorine’s left (5)
AFLAJ – first reverse JAFFA [orange], then make the second F(luorine) into L(eft). The plural form of FALAJ (!)
9 Book into large, rambling old Italian inn (7)
ALBERGO – B(ook) into (LARGE*) + O(ld)
10 After brief calm, I sob when losing pounds: the original sucker? (7)
LULIBUB – after LUL{l}, I B{l}UB. Old word for lollipop, one assumes
11 Scot’s bad meat that would be preserved if quietly stored (3)
KET – reverse cryptic: if you stored P [quietly] in KET you’d get KE{P}T [preserved]
12 Touching notes and informal apology about the author’s withdrawing something from Brewer’s? (11)
ZYMOSIMETER – RE [touching] + TE MI [(two) notes] + SOZ [informal apology] about MY [the author’s], the whole reversed.
14 Regularly seize catches soldier dropped when returning throw (6)
ZARAPE – {s}E{i}Z{e} “catches” PARA [soldier dropped], then reversed to find a word more often seen as SERAPE
15 Herbert Morrison’s last reforms for trade union members? (8)
BRETHREN – (HERBERT {morriso}N*)
17 Mocking of US lawman briefly and familiarly rock band does live (8)
NARQUOIS – NAR{c} + QUO [as in Status Quo, often “the Quo”] + IS [does live]
19 Area to take refuge in welcome when after time away from Wellington? (6)
BOOHAI – A “taking refuge in” HI, after BOO{t}, &lit, as this is is somewhere out in the sticks, in New Zealand
22 Trumpet-blowing bishop, his starting point maybe ball following dance music party (11)
BRAGGADOCIO – B(ishop) + C1 [where one bishop starts in a chess game] O [ball], following RAGGA DO [dance music | party]
23 Sturdy guy in drag, always taking the lead (3)
GID – G{uy} I{n} D{rag}. A disease of sheep
25 Miscellany found in a widow’s place, second from the right (7)
OMNIANA – A NAIN MO [a | widow’s place | second], reversed. Jesus raises the son of the widow of Nain from the dead in the Gospel of Luke
27 Milky food — and endless mint — one put out for visiting assortment of wildlife? (7)
MATZOON – first chop the end off MIN{t}, then put out the I [one] in favour of AT ZOO [visiting | assortment of wildlife]
28 Diss gap in letter order from Barbara Woodhouse? (5)
MUSIT – MU [letter] + SIT! [order from Barbara W]. A gap in a hedge or fence in East Anglia, where you’ll find Diss
29 Fox tailed around town in Oz plantation (9)
SALICETUM – STUM{p} around ALICE (Springs)
Down
1 So happy sunbather may lie down with bottom on rucksack! (5)
ABASK – A BAS [down with!, as in à bas le roi!] + {rucksac}K
2 Ref taking something to champ at end of game arranged by hosts (7)
ARBITER – BIT [something to champ] at {gam}E, “hosted” by ARR(anged)
3 Astronomer broadcast Mars latest info, then spoke (11)
HERTZSPRUNG – homophone of HURTS [mars] + S(top) P(ress) (?) + RUNG [spoke]
4 Southern ladies’ brother, ready for dropping off in Durham? (6)
SLOOMY – S LOO MY [southern | ladies’ | brother!]. Slumberous in Northern England
5 Fancy stern formula for centrepiece of unentertaining reflecting? (8)
APLUSTRE – reverse cryptic: A “plus” TRE will give you ATRE, which is hidden reversed in the middle of {unent}ERTA{ining}. An ornamental figurehead of a classical ship
6 Tool from the works you might pick up (3)
AWL – homophone of ALL [the works]
7 Ol’ Bert’s out to get ol’ Tommy! (7)
LOBSTER – (OL’ BERT’S*). A British soldier back in the day, red no doubt from baking under foreign suns
8 Drug requiring vaccination, alternatively with iodine (9)
JABORANDI – JAB OR AND I [vaccination | alternatively | with | iodine]
13 Making up stories on vacation, mostly all the same: mention work on return (11)
MYTHOPOETIC – M{ostl}Y + THO [all the same] + reversed CITE OP [mention | work]
14 Zulu out to capture Cape compound (4-5)
ZINC-BLOOM – Z(ulu) + IN BLOOM [out] “capturing” C(ape)
16 Angles ceased to be right: too short (8)
DIEDRALS – DIED [ceased to be] + R(ight) + ALS{o}
18 Students after misbehaving harm certain shrubs (7)
RHAMNUS – N.U.S. after (HARM*)
20 Seabird to take flight in pursuit of witch (7)
HAGBOLT – BOLT after HAG
21 Specifically ground grain when raising a poet’s kestrel, maybe wrongly? (6)
SCAMEL – SC. [specifically] + MEAL [ground grain], raising its A to the top. Gotta love dictionary words that are “a possible misprint in Shakespeare”
24 Area of ME, mostly sand that’s drifted over a mile (5)
DUNAM – DUN{e} over A M(ile). An Ottoman unit of area
26 Some tipped hot favourite to back (3)
AFT – hidden reversed in {ho}T FA{vourite}