Across:
8 Begins to leave agribusiness (‘begins’ to leave ‘agribusiness’ = arusis = RUSSIA) in Eastern Europe (RUSSIA),
9 Brief (n) show (‘screen’ without ‘n’= SCREE-) on church (-CH-) yard (-Y) (SCREECHY) sounds annoyingly harsh (SCREECHY),
10 Believers dismiss evils (‘believers’ dismiss ‘evils’ = beer = BEER) of the devil’s buttermilk perhaps (drink / BEER),
11 Doctor (= anagram indicator) in digs (in digs = DIS-ING) welcomes writers (-PENS-) (DISPENSING) giving out to the chemist (DISPENSING),
12 Bar (PU-B-) admits opening early (opening ‘Early’ = -E-) to draw attention (Lo! = -LO) (PUEBLO) to small-town Spain (PUEBLO),
14 Cooks someone’s goose (DESTROYS) with starter of delicacies (starter of ‘Delicacies’ = D-) and different (= anagram indicator) oysters (oysters = -ESTROYS) (DESTROYS),
15 A foreign (a = UN-) small (-S-) imp (-ELF-) is aware (-CONSCIOUS) (UNSELFCONSCIOUS) this shows a lack of embarrassment (UNSELFCONSCIOUS),
18 Crude (raw = WAR) review (= reversal indicator) by fun partner (Fun and GAMES) (WAR GAMES) of trial runs for a major employer (WAR GAMES),
20 Grace Kelly dismisses leak (‘Grace Kelly’ dismisses ‘leak’ = grcely = CLERGY) from service providers? (CLERGY),
22 One (I-) foreign politician (-MP-) on the edge (-RIM-) finds a (-A-) dull routine (rut = -TUR) upsetting (= reversal indicator) (IMPRIMATUR) and 20 across (‘clergy’) is responsible for sanctioning it (‘clergy’ grant licence to print religious book = IMPRIMATUR),
24 Of course (golf course / PAR-), the lead (‘The’ lead = -T) (PART) for one of those in the play (PART),
25 Welcomes (USHERS IN) you and me (US-) with that woman (-HER-) – is that wrong? (sin = -S IN) (USHERS IN),
26 Silent (silent = TINSEL) treatment (= anagram indicator) – the type that’s all for show (for show/superficial = TINSEL).
Down:
1 Lover boy (beau = B-EAU) entertaining old city (-UR-) (BUREAU) agency (BUREAU),
2 Ciphers removed in strip-search (‘ciphers’ removed in ‘strip search’ = stra = TSAR) of despot (TSAR),
3 Don’t touch (HANDS OFF) worker’s (workers = HANDS) switch (OFF) (HANDS OFF),
4 Goddess (Egyptian goddess of fertility = ISIS) has trouble getting out of boiler suits (‘trouble’ getting out of ‘boiler suits’ = isis = ISIS),
5 First goal (first ‘Goal’ = G-) leaves a bad smell in the air (-REEKS) (GREEKS) for Ajax and others (GREEKS),
6 China (TEA SERVICE) has a secretive (a secretive = TEA SERVICE) spill (= anagram indicator),
7 Whip (= anagram indicator) out hanky (out hanky = THANK YOU) in response to what you might be given (THANK YOU),
13 10 across (‘beer’ = BEER) and 21 down (‘garden’ = GARDEN) (BEER GARDEN) is for those not in The House who like a drink (BEER GARDEN),
14 Upsets (= reversal indicator) cross (rood = DOOR-) section initially (‘Section’ initially = -S) (DOORS) providing access to both Houses (DOORS),
16 Where you’d expect to find teacher’s pet (NEAR MISS) with a close one? (NEAR MISS),
17 Those working on 14 down (SECURITY work on ‘doors’) with Bond (SECURITY),
19 Graduate (M-A) gets to grips with institute (-I-) and the majority (most) briefly (t) (‘most’ without ‘t’ = -MOS-) (MIMOSA) from plant (MIMOSA),
21 Plant site (GARDEN) is out of (= anagram indicator) danger (danger = GARDEN),
23 Mentor leaves tournament (‘mentor’ leaves ‘tournament’ = tuna = TUNA) with one of the swimmers (TUNA),
24 Writers (PENS) lose it out of politeness (‘lose it’ out of ‘politeness’ = pens = PENS).