Across:
8 Juvenile (lad = LA-D-) paper’s (ID papers = -I-D-) lead: “Advice (lead ‘Advice’ = -A) (LA-DI-DA) can be pretentious, in a manner of speaking” (LA-DI-DA),
9 The foreign- (the = EL-) -edited (= anagram indicator) quote (quote = -OQUE-T) about Nationalist leader (‘Nationalist’ leader = -N-) (ELOQUENT) is persuasive, whatever you say (ELOQUENT),
10 De Gaulle fails to get deal (‘De Gaulle’ fails to get ‘deal’ = gule = GLUE) to stick (GLUE),
11 Do it fine in (do it fine in) sporty (= anagram indicator) (do it fine in = DEFINITION) Focus (DEFINITION),
12 Reduce (d) tempo (‘speed’ without ‘d’ = SPEE-) for church (-CH) (SPEECH) sermon (SPEECH),
14 Sensible (RATIONAL) quota (RATION-) for a (-A-) Liberal (-L) (RATIONAL),
15 A French- (a = UN-) -German article (the = -DER-) on the advantaged (-PRIVILEGED) (UNDERPRIVILEGED) is really poor (UNDERPRIVILEGED),
18 Those in the student block (SCHOLARS) looking to pick up the post in Dean’s Place? (SCHOLARS / post in dean’s place/college),
20 Three-quarters of those in 17 down (three-quarters of those in ‘importer’ = PORTER) working in a station (PORTER),
22 Grecian map (Grecian map) adapted (= anagram indicator) (Grecian map = CAMPAIGNER) by one of The Crusaders (CAMPAIGNER),
24 Elvis Presley dismissed severely (‘Elvis Presley’ ignored ‘severely’ = lisp = LIPS) by mouthpieces (LIPS),
25 Cornea is (cornea is) damaged? (= anagram indicator) (cornea is = SCENARIO) One of those in theatre outlined this possibility! (SCENARIO),
26 Consequence (EFFECT) of retiring (= reversal indicator) Lawrence (TE Lawrence = TE = E-T) welcoming Clare (CE = -EC-) to party (Fianna Fáil = -FF-) (EFFECT).
Down:
1 What the Arabian might do (Arabian horse might GALLOP) left (-L-) in foreign (= anagram indicator) gaol (gaol = GA-LO-) by political leader? (‘Political’ leader = -P) (GALLOP),
2 Engage the services (HIRE) of gal from Raleigh (‘gal’ from ‘Raleigh’ = reih = HIRE),
3 It’s not easy (HARD-) to begin show (begin ‘Show’ = -S-) for trendy (-HIP) (HARDSHIP) Dire Straits (HARDSHIP)
4 Content in schedule affected (content in ‘scheduLE AFfected’ = LEAF) – that’s one for the books (LEAF),
5 Insect (HORNET) is not her (not her) problem (= anagram indicator) (not her = HORNET),
6 Persuade someone to buy (AUCTION-) ale (beer) with no head (b) (‘beer’ without ‘b’ = -EER) (AUCTIONEER) – presumably one has lots to sell? (AUCTIONEER sells lots at an auction),
7 Introduce new ideas (INNOVATE) to public house (INN-) opening off-licence (opening ‘Off-licence’ = -O-) holding wine (-VAT-) from Spain (-E) (INNOVATE),
13 It’s astonishing (EYE-POPPING) to check out (to EYE-) music (POP- music) press (press/hold = -PIN-) ahead of gig (ahead of ‘Gig’ = -G) (EYE-POPPING),
14 Freudians fade away (‘Freudians’ ‘fade’ away/without ‘fade’ = ruins = RUINS) from breakdowns? (RUINS),
16 Impossible (NO CHANCE) to set-up (= reversal indicator) broadcast (on = NO) opportunity (CHANCE) (NO CHANCE),
17 The one taking it all in (IMPORTER) rejects (= reversal indicator) road (MI= IM-) taken by drinker (-PORTER) (IMPORTER),
19 News agency (Associate Press = AP-) with revolutionary (= reverse indicator) first-class (AI = -IA-) writing (from the 3Rs = -R-), is ticked off by voter (yes = -Y) (APIARY) creating quite a buzz presumably (APIARY),
21 Plan for (EXPECT) former (EX-) teacher’s favourite (pet = -PE-T) embracing college (-C-) (EXPECT),
23 One of the bright lights (NEON) in libertine ontology (in ‘libertiNE ONtology’ = NEON),
24 Rifle shot misses horse? (‘rifle shot’ misses ‘horse’ = iflt = LIFT) That’ll raise spirits! (LIFT).