Across:
8 Type of toast (FRENCH toast), in a manner of speaking, in Canada (FRENCH),
9 Suits (playing cards / DIAMONDS) in 15 across for starting (‘diamond polisher’ for starting = DIAMOND-) school (-S) (DIAMONDS),
10 Charming (CUTE) centaur ran away (‘centaur’ ‘ran’ away/without ‘ran’ = cetu = CUTE),
11 Mitch (PLAY TRUANT) to take dramatic role in (PLAY) The Fugitive outside school (TRUANT) (PLAY TRUANT),
12 Rear admiral dismisses alarm (‘rear admiral’ dismisses ‘alarm’ = reardi = RAIDER) produced by pirate (RAIDER),
14 Secretary (PA-) gets temporary lease (-RENTAL) (PARENTAL) of life – support you’d associate from The Elders (PARENTAL support),
15 One of those outstanding types in Ring (one of those outstanding types in wedding ring = DIAMOND) and 25 across (‘polisher’ = POLISHER) (DIAMOND POLISHER) finishes with The Stones (DIAMOND POLISHER),
18 Stop living (die = DI-E) over barman (Senior Counsel = -SC-) at address (-IP- address) with novice (learner = -L) (DISCIPLE) – a faithful follower (DISCIPLE),
20 Red-tailed black sharks (FISHES) sound (= homophone indicator) almost vicious! (‘vicious’ sounds almost like ‘fishes’ = FISHES),
22 Musicians (RAP ARTISTS) writing (from the 3Rs = R-) to a (-A-) tenor (-T-) in Paris (Paris = -P AR-IS-) on back (= reverse indicator) street (St = -TS) (RAP ARTISTS),
24 She is taken off coaches’ (‘she’ is taken off ‘coaches’ = coac = COCA) stimulant (cocaine from COCA shrub),
25 One doing a job on The Gloss (POLISHER), in manner of speaking (POLISH-), in hospital (-ER) (POLISHER),
26 The Star-Spangled Banner (US national ANTHEM) is obviously a type of country music? (ANTHEM).
Down:
1 A (-A-) first at university (first at ‘university’ = -U-) in store (store/ mart = TRA-M-) – looking back (= reverse indicator) (TRAUMA), presumably, that comes with a lot of pain (TRAUMA),
2 Some time ago (ONCE) confined in detention centre (confined in ‘detentiON CEntre’ = ONCE),
3 Guard of honour perhaps (CHAPERON) for man (chap = CHAP-) confusing (= anagram indicator) Nero (Nero = -ERON) (CHAPERON),
4 Part of upsetting (= reverse indicator) dilemma editing (part of upsetting ‘dilemmA EDIting’ = aedi = IDEA) what someone using their head thought (IDEA),
5 Hotel (H-) make changes (-ALTER) (HALTER) stopping Arabian in tracks (stopping Arabian/horse in tracks HALTER),
6 Hacks (COLUMNISTS) writer’s forum (COLUMN-) for academic achievements (Firsts = 1sts = -ISTS) (COLUMNISTS),
7 Armadillo, for instance (EDENTATE), from The Garden (Garden of EDEN-) State (state) needs no introduction (s) (‘state’ without ‘s’ = -TATE) (EDENTATE),
13 Funny (= anagram indicator) comedic art (comedic art = DEMOCRATIC) is systematic of a structure of government (DEMOCRATIC),
14 Those cocooning (PUPAE) with the young boxer (PUP-) Russell (George William Russell = -AE) (PUPAE),
16 Sets up (= reverse indicator) personnel schedule (rota = -ATOR) limiting (e) time (‘time’ without ‘e’ = tim = -MIT-) on one (I-) (IMITATOR) copier (IMITATOR),
17 Take your time, for instance (LIFESPAN), producing biography (LIFE-) rotating (= reverse indicator) regular breaks in the afternoon (naps = -SPAN) (LIFESPAN),
19 Settle bill (PA-Y) covering initial travel (initial ‘Travel’ = -T-) to Switzerland (-CH-) (PATCHY) that’s not consistent along the way (PATCHY),
21 Steer clear of (ESCHEW) English (E-) plant (sow) audible (= homophone indicator) (‘sow’ = ‘sew’ = -S-EW) around church (-CH-) (ESCHEW),
23 Rank (SORT) of Marshal? (marshal/put in order = SORT),
24 Allude to (CITE) State’s (= homophone indicator) vision (‘sight’ = ‘CITE’).