Across:
1 Weird (ODDITY) old (O-) deputy head (‘Deputy’ head = -D-) from college (Dublin Institute of Technology = -DIT-) with ponytail (‘ponY’ tail = -Y) (ODDITY),
4 Came by (OBTAINED) to get one’s hands on (OBTAIN-) Oriental (east = -E-) starter dish (starter ‘Dish’ = -D) (OBTAINED),
9 Political exile (ÉMIGRÉ) offering regime (regime = ÉMIGRÉ) change (= anagram indicator),
10 From an educational prospective, master (GRADUATE) butcher (= anagram indicator) argued (argued = GRADU-E) over a (-A-) bone (-T- bone) (GRADUATE),
12 Acknowledges the audience (TAKES A BOW) – is that what one of those on the fiddle does? (TAKES A BOW),
13 Subject (THEME) to helpmate getting rid of pal (‘helpmate’ getting rid of ‘pal’ = hemte = THEME),
14 Postman (MAN OF LETTERS) reads the good stuff? (MAN OF LETTERS),
18 Trust (FAITH) doctors (HEALERS) (FAITH HEALERS) – those appealing to higher-ups for the betterment of others (FAITH HEALERS),
21 Is out there (OVERT) to lift lid off (c) secret (‘covert’ without ‘c’ = OVERT),
22 Throw light on (IRRADIATE) awful (= anagram indicator) air raid (air raid = IRRADIA-) on square (-T- square) to the East (-E) (IRRADIATE),
24 Hospital (H-) nursed (nursed = -UNDRE-S) sick (= anagram indicator) – around 500 (500 = Roman D = -D-) (HUNDREDS) or some such number (HUNDREDS),
25 Tibetans lose it (‘Tibetans’ lose ‘it’ betans = ABSENT) when not in attendance (ABSENT),
26 Has an inclination (HILLSIDE) this is for the Dublin supporters (HILL-) and Kerry (-SIDE) (HILLSIDE),
27 Really cared about (MINDED) what’s at the bottom of 11 down (bottom of ‘absent-minded’ = MINDED).
Down:
1 Throughout our existence (OVER TIME), this is all we get for working longer (OVERTIME),
2 Taking in Manhattan, for example (taking in Manhattan cocktail = DRINKING), with doctor (DR-) popular (-IN-) on the board (-KING on chess board) (DRINKING),
3 Lay to rest without a lot (‘lay to rest’ without ‘a lot’ = yrest = TYRES) of those spares synonymous with The Boot? (spare TYRES),
5 Kiwi (BIRD-) at The Observer (-WATCHER-) is half (‘iS’ half = -S) (BIRDWATCHERS) interested in the tweeters (BIRDWATCHERS),
6 The theatre’s (the theatres = AUDITORIA) bookkeeper (AUDITOR-) flips over (= reversal indicator) initial insult (initial ‘Insult’ = -I-) from leading actor (leading ‘Actor’ = -A) (AUDITORIA),
7 Northern (N-) person who could be picky (-EATER) (NEATER) is more into The Order (NEATER),
8 Person named in Berlin (DIETER) has the potential to be a good loser (DIETER),
11 Daydreaming (ABSENT-MINDED) in 25 across? (‘absent’ = ABSENT-) Took umbrage with that! (-MINDED) (ABSENT-MINDED),
15 What you get for taking the rocky road to Dublin, for instance? (FLAT TYRES) Accommodation (FLAT) in 3 down (‘tyres’ = TYRES) (FLAT TYRES),
16 Sounds like advice to someone losing the loaf (get a head / GET AHEAD) to achieve? (GET AHEAD),
17 Raised (ASSERTED) fool (ASS-) in hospital (-ER-) – the one loving Elvis (fan of Elvis = Teddy Boy = -TED) (ASSERTED),
19 Finish off (f) local dance (‘hoof’ without ‘f’ = HOO -) last of all with euphoria, flourish (last of all ‘witH euphoriA flourisH’ = - HAH) (HOO-HAH) and excitement (HOO-HAH),
20 Florentine removes trio (‘florentine’ removes ‘trio’ = flenne = FENNEL) from herb garden (FENNEL),
23 Person found in monk’s town (person found in Monkstown = DUB-) with excellent (-AI) (DUBAI) port from the east (DUBAI).