Across:
8 Old city (-UR-) in Belgium (BE = B-E-) with American (-A-) university (-U) (BUREAU) department (BUREAU),
9 Croaky (hoarse) on the radio (= homophone indicator) (‘hoarse’ = ‘HORSE-‘) and on local television (-BOX) (HORSEBOX) in the trailer for Black Beauty, presumably (HORSEBOX),
10 Charity’s plea (GIVE) to all from village (‘all’ from ‘village’ = vige = GIVE),
11 Old examination (Inter Cert exam = INTER-) associated with good books (New Testament = -N-T) consumes grown-up boys (-MEN-) (INTERNMENT) leading to detention (INTERNMENT),
12 Get it in the neck (THROAT) over (= reverse indicator) Chinese philosopher’s ideal (Tao = -OAT) retweet (rt = T-R-) about hothead (‘Hot’ head = -H-) (THROAT),
14 EU dismissed by unsuitable (‘EU’ dismissed by ‘unsuitable’ = nsuitabl = ISTANBUL), old capital (ISTANBUL),
15 Severely reprimand (GIVE SOMEONE HELL) 10 across (‘give’ = GIVE) for an unspecified person (SOMEONE) from 23 down (‘hell’ = HELL) (GIVE SOMEONE HELL),
18 A (-A-) couple of Frenchmen (Messieurs = -MM-) in Press (press) Box (= anagram indicator) (press = SP-ERS) (SPAMMERS) synonymous with The Mail no one wants (SPAMMERS),
20 Not the first (‘Not’ the first = n) to leave Italian port (Naples) (‘Naples’ without ‘n’ = -APLES) after (= position indicator) Mass (M-) (MAPLES) for members of The Acer family (MAPLES are members of the acer family of trees),
22 Local holds down a second job (MOONLIGHTS) producing first movie (first ‘Movie’ = M-) shooting (shooting) out (= anagram indicator) (shooting = -OON-IGHTS) around Lima (-L-) (MOONLIGHTS),
24 Forbids (BARS) public houses serving drink (BARS),
25 Romeo (R-) emailed (emailed) boss (= anagram indicator) (emailed = -EMEDIAL) (REMEDIAL) – it’s meant to be therapeutic (REMEDIAL),
26 Tease (kid = KI-D) over club (-C-) going to Kildare (-KE-) (KICKED) to put the boot in (KICKED).
Down:
1 It's fine, for example (fine/penality = PUNISH), to sell drugs (PU-SH) around Ulster (Ulster = Northern Ireland = -NI-) (PUNISH),
2 Sides with Henry of Navarre (sides with ‘HEnry of navarRE’ = HERE) on this spot (HERE),
3 Half (CUT IN TWO) of Split (CUT IN TWO),
4 It’s the complete opposite of those characters fronting 13 down (it’s the complete opposite of those fronting ‘open-minded’ = open + opposite of open = SHUT) and bar (SHUT),
5 Soldier (para) loses the head (p) (‘Para’ without ‘p’ = ARA-) with sailor (tar) over (= reverse indicator) (tar = -RAT) (ARARAT) where Noah landed (ARARAT),
6 Names a (names a) cocktail (= anagram indicator) (names a = SEAMAN-) opening seedy (opening ‘Seedy’ = -S-) joint (-HIP joint) (SEAMANSHIP) with the type of skill one needs if they’re taking a punt? (SEAMANSHIP needed if taking a punt/boat),
7 Heads, joints, organs, hoofs, necks (heads/first letters of ‘Joints Organs Hoofs Necks’ = JOHN) from farm animal (BULL) (JOHN BULL) typically found in England (JOHN BULL),
13 Willing to consider new types in 14 down (willing to consider new ‘ideas’ = OPEN-MINDED) for Frank (OPEN-) and Old Penny (£SD / old penny = -D-) dressed-up (= reversal indicator) in denim (denim = MIN-ED) (OPEN-MINDED),
14 Characters in Odessa edited (characters in ‘odesSA EDIted’ = saedi) Review (= reversal indicator) (saedi = IDEAS) of Theories (IDEAS),
16 Goes here and there (-ROVES) following (= position indicator) mischievous type (IMP-) (IMPROVES) to rallies (rallies/recovers = IMPROVES),
17 Important person (NAME-) on the drink in Tokyo (-SAKE) (NAMESAKE) has the same signature as Louis XIII, for example? (NAMESAKE),
19 Get the answer from (ELICIT) Felicity (Felicity) cutting margins (‘f+y’) (‘FelicitY’ cutting ‘f+y’ = ELICIT),
21 Uplifting (= reverse indicator) study (den = -NED) by Rex (-R-) Russell (George William Russell = AE = EA-) (EARNED) gained through his work (EARNED),
23 Thrilled to remove dirt (‘thrilled’ to remove ‘dirt’ = hlle = HELL) accommodating the man downstairs (the man downstairs = devil + living in HELL),
24 King Cobra has no groin (‘King Cobra’ has no ‘groin’ = kcba = BACK) or vertical column? (BACK).