Quite a few candidates for Clue of the Day as a result; I was very impressed by 10ac (there was an unusual number of high quality homophone clues throughout, in fact) and 22dn, but I think the top award from me really has to go to 4dn where “ragged” contributes to the surface reading if you pronounce it one way, or acts as an anagrind if the other – what a superb &lit clue!
ACROSS
1 Censures concerning academics repeating nothing (8)
REPROOFS – RE PROFS [concerning academics], but with the O repeated
5 One getting in the groove playing lusty lead in story (6)
STYLUS – (LUSTY*) [“playing”] + S{tory}
9 Employees having time for painting accessories (8)
STAFFAGE – STAFF [employees] having AGE [time]. The simplest possible wordplay for quite an obscure word!
10 What can go with a bit of the match broadcast (6)
BRIDLE – homophone of BRIDAL [of the match]
12 William, killed hunting game, tailed grouse (5)
RUFUS – RU [game] + FUS{s} [“tailed” grouse]. That’s William Rufus as in William II.
13 Waste no time visiting daughter in decline (3,2,4)
RUN TO SEED – RUN TO SEE [waste no time visiting] + D [daughter]
14 Just past tree, men with the trailer (2,1,5,4)
BY A SHORT HEAD – BY ASH OR [past | tree | men] with THE AD [the | trailer]
18 Swell new offer blocked by pro? That mustn’t happen! (6,6)
HEAVEN FORBID – HEAVE N BID [swell | new | offer] “blocked by” FOR [pro]
21 Best, once again, note, to study inquiry briefly (9)
RECONQUER – RE CON QUER{y} [note | to study | inquiry “briefly”]
23 Take the part of a basin which fills with water (5)
PLAYA – PLAY A [take the part of | a]
24 Horn put out note, holding firm? Hardly! (6)
KLAXON – K.O. N [put out | note], “holding” LAX [firm? hardly!]
25 Canadian native coming across a person with whistle and light (8)
CAREFREE – CREE [Canadian native] “coming across” A REF [a | person with whistle]
26 Job to follow this wild-west hero’s part (6)
ESTHER – hidden in {wild-w}EST HER{o’s}. Being the book of the Bible that precedes Job.
27 Sickly after vacation, blames bad diet (8)
ASSEMBLY – (S{ickl}Y + BLAMES*) [“bad”]
DOWN
1 Succeeded in shouting a string of requests etc (6)
ROSARY – S [succeeded] in ROARY [shouting]
2 Irrational blunder deposing leader: one’s executed on the spot (6)
PIAFFE – PI {g}AFFE [irrational | blunder, “deposing leader”]
3 Historic defence beginning when king covered in woad? (5,4)
OFFA’S DYKE – OFF AS [beginning | when] + K [king] “covered in” DYE [woad?]
4 Four endlessly suffering when ragged? (7,2,3)
FIGURES OF FUN – (FOU{r} + SUFFERING*) [“ragged”], &lit
6 Part of engine died: track going uphill (5)
TURBO – OB RUT [died | track], all reversed
7 Ran, directed outside summer shows (8)
LADDERED – LED [directed] “outside” ADDER [summer]
8 Relatives rung by prosecutor and detective (8)
STEPDADS – STEP [rung] by DA [prosecutor] and DS [detective]
11 There’s no chance of that Roy getting off with nursemaid! (2,4,6)
IN YOUR DREAMS – (ROY + NURSEMAID*) [“getting off”]
15 End of yarn still to be picked up (9)
TAILPIECE – homophone of TALE PEACE [yarn | still]
16 Brave of Nancy’s dear old chief to speak out (8)
CHEROKEE – CHER [Nancy’s, i.e. French word for, dear] + O [old] + homophone of KEY [chief]
17 Noble bringing in woman who’ll do diagram (3,5)
BAR CHART – BART. [noble] “bringing in” CHAR [woman who’ll do]
19 Capital letters at either end on short flyer (6)
ZAGREB – Z A [letters at either end (of the alphabet)] on GREB{e} [“short” flyer]
20 Through stuffing bird, cracks appear (6)
JAPERY – PER [through] “stuffing” JAY [bird]
22 Oscar using something hooked sometimes for a coat hanger (5)
NOOSE – O [Oscar] using NOSE [something hooked sometimes] “for a coat”
Ok, I’m not that good obviously, but never gave up, and never looked anything up, except to confirm a word in the dictionary.
Ordinary bloke