Across:
8 Hound (ANIMAL) most of the characters at the end of 15 across (most of the characters at the end of ‘domestic animals’ = ANIMAL),
9 Home (DOMESTIC) at the start of 15 across (start of ‘domestic animals’ = DOMESTIC),
10 Georgian ignores Erin (‘Georgian’ ignores ‘Erin’ = goga = AGOG) waiting with bated breath (AGOG),
11 Tom (CAT-) English (-E-) is (-IS-) taken in by butchery (butchery/gore = -GOR-E) (CATEGORISE) class (CATEGORISE),
12 Flipping (= reversal indicator) over the top (over the top = OTT = -TTO) or (OR = -RO-) initially gratuitous (initially ‘Gratuitous’ = G-) (GROTTO) for visiting dancer’s boss? (Santa’s GROTTO),
14 They are capable of wiping the floor (CLEANERS) with those who know how much DIRT needs to be collected (CLEANERS),
15 Family quarrels (domestics = DOMESTIC -S) over a Milan (a Milan) adaptation (= anagram indicator) (a Milan = ANIMAL-) (DOMESTIC ANIMALS) of A Thousand and One Dalmatians, for example (DOMESTIC ANIMALS),
18 4 down (‘edit’ = EDIT-) is charged (-ION-) for taking school (-S) (EDITIONS) year books, for instance (EDITIONS),
20 Lock-up (GARAGE) legend (‘leG’ end = G-) with a (-A-) bad temper (-RAGE) (GARAGE),
22 Not straight (bent = B-ENT) about Niamh’s (Niamh’s) play (= anagram indicator) (Niamhs = ANISHM-) sent (BANISHMENT) out of the country (BANISHMENT),
24 The Gathering (CROP) in The Acropolis (part of ‘the aCROPolis’ = CROP),
25 Where you might find one of those major types (ON PATROL) working the beat (ON PATROL),
26 A (A-) medium (-M-) in Middle Eastern country (Iran = -IR-AN) (AIRMAN) has head in the clouds perhaps (AIRMAN).
Down:
1 Regan (regan = -NAGER) and Goneril – the second (‘gOneril’ – the second = O-) playing up (= reverse indicator) (ONAGER) with Medieval catapult (Medieval catapult = ONAGER),
2 Self-righteous (SMUG) hints from gunsmiths (‘hints’ from ‘gunsmiths’ = gusm = SMUG),
3 Screen (BLOCK OUT) key (music key B-) event for the workers before first World War in Dublin (-LOCK OUT) (BLOCK OUT),
4 In part got ideas (in part ‘goT IDEas’ = tide) looking back (= reverse indicator) (tide = EDIT) from Polish prose? (polish prose = EDIT),
5 Turns up (= reverse indicator), from the start, Eliot (from the start ‘Eliot’ = -E) and Frost (frost = rime = EMI-R-) got hold of graphic introduction (‘Graphic’ introduction = -G-) (ÉMIGRÉ) produced by political exile (ÉMIGRÉ),
6 Night-watchman (ASTRONOMER) spends a lot of time looking into space (ASTRONOMER),
7 Troubadour (MINSTREL) and tenor (-T-) involved in Merlin’s (Merlins) destruction (= anagram indicator) (Merlins = MINS-REL) (MINSTREL),
13 Brief (m) them (‘them’ without ‘m’ = THE-) to get answer (-A-) from criminal leader (‘Criminal’ leader = -C-) in court case (-TRI-AL) (THEATRICAL) playing to the gallery (THEATRICAL),
14 Train from Costa Rican (‘train’ from ‘Costa Rican’ = cosca = COCAS) plants synonymous with the drug-making business (COCAS),
16 Hold (hold) off (= anagram indicator) (hold = OLD H-) taking relative (-AUNT) (OLD HAUNT) to a place one never left in the past (OLD HAUNT),
17 Odd (= anagram indicator) thing (thing = NIGHT-) for accountant (-CA-) to post (-P) (NIGHTCAP) with late tot (NIGHTCAP),
19 Those relatives (mothers) losing the head (m) (‘mothers’ without ‘m’ = OTHERS) may be significant (significant OTHERS),
21 Rewritten (= anagram indicator) blog (blog = GLOB-) for a (-A-) novice (learner = -L) (GLOBAL) with general view (GLOBAL),
23 No end to the needles (no ‘end’ to the ‘needles’ = eles = EELS) with the long swimmers (EELS),
24 Find fault (CARP) with one of those in school (CARP fish in school of fish).