Across:
8 Short (LITTLE) mini (LITTLE),
9 Lead guitarist (lead ‘Guitarist’ = -G-) in German city (Hanover = HAN-OVER) (HANGOVER) calls out for The Cure (HANGOVER),
10 Spots (RASH) half of those in 3 down (half of ‘heat rash’ = RASH),
11 Freudian’s (Freudians/analysts = THERAPISTS) article (THE-) on music (-RAP-) gets awards from university (firsts = 1sts = -ISTS) (THERAPISTS),
12 Exercise (physical education = PE-) institute (-I-) in African republic (Republic of South Africa = RSA = -RS-A) (PERSIA) – an old country that changed its name (PERSIA),
14 Rocky (UNSTABLE) from a foreign (‘a’ foreign = UN-) group of boxers with the same trainer, for instance (-STABLE of boxers) (UNSTABLE),
15 Helping people to talk (SPEECH THERAPIST) to 26 across (‘speech’ = SPEECH) and one of those in 11 across (one of ‘therapists’ = THERAPIST) (SPEECH THERAPIST),
18 Room (SPACE) near where drink is served (BAR) (SPACE BAR) in The Long Key (SPACE BAR),
20 Would you like to volunteer (ANYONE!) in (A-) city in America (New York = -NY-) to join unit? (-ONE) (ANYONE),
22 What one might do with red eye (FLY-BY-NIGHT) of cowboy? (FLY-BY-NIGHT),
24 Pressure (HEAT) from half of those in 3 down (half of ‘heat rash’ = HEAT),
25 Porter (stout = ST- OUT) carrying old (-O-), old (-O-) handbag in the middle (‘hanDbag’ in the middle = -D) (STOOD OUT) was conspicuous (STOOD OUT),
26 Sheep (sheep) running (= anagram indicator) (sheep = SPEE-H) around Clogherhead (‘Clogher’ head = -C-) (SPEECH) address? (SPEECH).
Down:
1 Broad side (broadside = TIRADE) and top on Isuzu (top on 'Isuzu' = -I-) in traffic (T-RADE) (TIRADE),
2 Desire (ITCH) for what you might have got with 3 down (get ITCH from ‘heat rash’),
3 Allergic reaction (RASH) to passion? (HEAT) For starters (= position indicator) (HEAT RASH), you’d get that from The Sun! (HEAT RASH)
4 Fat (GHEE) in T-shirt from High Street? (‘T-shirt’ from ‘High Street’ = ghee = GHEE),
5 Eavesdropping for a gent (‘a gent’ = ‘agent’) covertly (eavesdropping for agent/spy = PHONE TAPPING) hearing things from others online? (hearing things from other on telephone line = PHONE TAPPING),
6 Bankrolls The Tourists’ (HOLIDAY PAY) wages for touring? (HOLIDAY PAY),
7 Taipan’s (taipans/snakes = REPTILES) agent (REP-) for mosaic material (-TILES) (REPTILES),
13 Small (S-) crafty sort (-KETCH-) gets to show disapproval (-BOO-) to keen beginner (‘Keen’ beginner = -K) (SKETCHBOOK) in the drawing-room’s library presumably (SKETCHBOOK),
14 Escort (USHER) is well (gusher) off from the start (g) (‘gusher’ without ‘g’ = USHER).
16 Music (POP-) at university (University of Limerick = -UL-) consumed (-ATE) (POPULATE) by people (POPULATE),
17 It’s an indication of how good the coach is working (ROAD TEST), by the way (ROAD), at trial (TEST) (ROAD TEST)
19 Those getting a beating (BONGOS) in brief (x) fight (box) (‘box’ without ‘x’ = BO-) with Amnesty and others (non-profit organizations = NGOs = -NGOS) (BONGOS),
21 A subtle difference (NUANCE) to religious person (nun = NU-N-) over a (-A-) church (Church of England = -CE) (NUANCE)
23 Spirits (GUTS) in bottle? (GUTS),
24 Trader from horse trade (‘trader’ from ‘horse trade’ = hose = HOES) works in the garden (HOES).