Across:
8 Rows or (rows or = SORROW) upsets (= anagram indicator) produced misery (SORROW),
9 Harm one’s (harm ones = HORSEMAN) rig (= anagram indicator) getting Arabian to go faster perhaps (HORSEMAN),
10 Give someone a hard time (nag = GAN-) retiring (= reversal indicator) from Government (-G) (GANG) circle (GANG),
11 Can do without (EXPENDABLE) former partner (EX-), as writer (-PEN-) and director (-D-) up to the job (-ABLE) (EXPENDABLE),
12 Buy into (SNAP UP) what Venus flytrap will do for you (SNAP UP),
14 Say one has the right (LAY CLAIM) place (LAY) to land to look for gold (CLAIM) (LAY CLAIM),
15 Walk across the road (PELICAN CROSSING) with the bird (PELICAN) at Checkpoint Charlie (CROSSING) (PELICAN CROSSING),
18 Fast, vile (fast, vile = FESTIVAL) criminal (= anagram indicator) in Fiesta (fiesta = FESTIVAL),
20 No Asians in San Sebastian (no ‘Asians’ in ‘San Sebastian’ = nebsta = ABSENT) on holiday (ABSENT),
22 Provided financial security (GUARANTEED) for policeman (GUAR-D) protecting worker (-ANT-) on drugs (-EE-) (GUARANTEED),
24 Supports without spur (‘supports’ without ‘spur’ = pots = POTS) in greenhouse containers (POTS),
25 Network (WEB-) refers to (“cites” = “sites” = SITES) reports (= homophone indicator) (WEBSITES) of destinations for surfers (WEBSITES),
26 100 (100 = Roman C) leaving university department (‘faculty’ missing ‘c’ = FAULTY) can’t be right (FAULTY).
Down:
1 Gangster (DO-N) admits tipping off many an individual (tipping off/first letters of ‘many an individual’ = -MAI-) (DOMAIN) from estate (DOMAIN),
2 Draw (draw/haul = DRAG) is a pain in the neck (DRAG),
3 Dessert (SWEET-) with fruit (pear) is not finished (r) (‘pear’ without ‘r’ = -PEA) (SWEETPEA) with the fragrant colourful flowers on the rise (SWEETPEA),
4 Outlet (SHOP) for posh (posh = SHOP) cocktail (= anagram indicator),
5 By and large, Gale is missing, (‘by and large’, without ‘Gale’ = byandr = BRANDY) in spirit (BRANDY),
6 The first three (MEDALLISTS) award winners (MEDALLISTS),
7 Mark (mark/symbol = SIGN) Bellow (CALL) from the start (= positional indicator) (CALL SIGN) is employed by radio station (CALL SIGN),
13 Decorator (PAINTBRUSH) suffering (PAIN-) from infectious disease (-TB-) in Dublin (-RUSH) (PAINTBRUSH),
14 Sounds almost like (= homophone indicator) it could be of interest to someone on a diet (“low cal” = “lo cal” = LOCAL) in the neighbourhood (LOCAL),
16 Puts the plan into action (EXECUTES) for directors (executives) dismissing four from Rome (Roman four = IV) (‘executives’ without ‘iv’ = EXECUTES),
17 Switch (switch ON) from a (A-) new (-N-) party (-D O-) to another party? (Fianna Fáil = -FF) (ON AND OFF) That’s how some unions work! (ON AND OFF),
19 Narcissism (VANITY) of one (-I-) from the capital (‘the’ capital -T-) in navy (navy = VAN-Y) dress (= anagram indicator) (VANITY),
21 Write something (NOT-E) about A- (-A-) -Team leader (‘Team’ leader = -T-) (NOTATE) and arrange it for a musical (NOTATE),
23 There’s a comfort (EASE) in area settlement (in ‘area settlement’ = EASE),
24 Shoot local (shoot ‘local’ = PLUG) from Cork (cork = PLUG).