Across:
8 Order it officially (ORDAIN) for new (= anagram indicator) road (road = ORDA-) going up (= reversal indicator) north (NI = -IN) (ORDAIN),
9 Heads to Catania, Rimini, Imola (heads to ‘Catania Rimini Imola’ = CRI-) and Milan (Milan) working (= anagram indicator) (Milan = -MINAL) (CRIMINAL) for The Don (CRIMINAL),
10 Exhibited the effects of time (AGED) consumed by mortgage debt (consumed by ‘mortgAGE Debt’ = AGED),
11 Those closing deals (HANDSHAKES) for 2 down (‘hand’ = HAND-) taking direction (South = -S-) from those in school (-HAKES in ‘school’ of fish) (HANDSHAKES),
12 Raised (= reverse indicator) two offspring (kid + kid = DIK-DIK) of an antelope (DIK-DIK dwarf antelope),
14 Comes (COM-ES) across dog (-PET-) (COMPETES) that has a chance of winning (COMPETES),
15 Parting gift (GOLDEN HANDSHAKE) from 26 across (‘golden’ = GOLDEN) and most of those in 11 across (most of those in ‘handshakes’ = HANDSHAKE) (GOLDEN HANDSHAKE)
18 Standard (STOCK-) drugs (-POT) (STOCKPOT) for those on the sauce in the kitchen perhaps (STOCKPOT),
20 Spill the beans on (EXPOSE) former (EX-) model (-POSE) (EXPOSE),
22 Mediates (ARBITRATES) with a bar sitter (a bar sitter) drunk (= anagram indicator) (a bar sitter = ARBITRATES),
24 Closes 6 down (closes ‘pirate ship’ = SHIP) for Pink, the crafty older type? (‘pink’ is a small square-rigged sailing SHIP),
25 Counter- (TABLETOP) -attack (= anagram indicator) battle (battle = TABLET-) on rising (= reverse indicator) river (River Po = -OP) (TABLETOP),
26 Donegal dropping a (‘Donegal’ dropping ‘a’ = donegl = GOLDEN) colourful type (GOLDEN).
Down:
1 Two sides to gringo’s (two sides/two halves to ‘gringo’ = ‘gri’ x 2 = GRI-GRI) devilish charm (GRI-GRI),
2 Straight (poker HAND) mole from Homeland (‘mole’ from ‘Homeland’ = hand = HAND),
3 Is not disturbed (UNSHAKEN) by organisation (United Nations = UN-) getting upset (-SHAKEN) (UNSHAKEN),
4 Celebrity (ICON) turns up (= reverse indicator) in San Marino City (in ‘san mariNO CIty’ = noci = ICON),
5 Revolutionary (= reverse indicator) Frenchmen (MM = -M-M) taking in America (US = SU-) get papers (ID papers = DI-) (DIM SUM) served in Chinese restaurant (DIM SUM),
6 One of those employing 19 down (PIRATE SHIP employing ‘pirate’) in park (P-) is seeing red (-IRATE) having to deliver (deliver = SHIP) (PIRATE SHIP),
7 Measure (TAPE) what’s found on 24 across (DECK found on ‘ship’) (TAPE DECK) by old music producer (TAPE DECK),
13 Takeaway (DEDUCT-) opens before lunch (opens ‘Before Lunch’ = -BL-) in Ireland (Ireland domain = .ie = -I-E) (DEDUCTIBLE) and the Revenue is having none of it (DEDUCTIBLE),
14 Cold (C-) heart (heart) – it’s said (= homophone indicator) (‘heart’ = ‘hart’ = -HART) (CHART), 6 down has one of them (‘pirate ship’ has CHART),
16 Exposed (OUT-) by Shatter? (shatter = -BREAK) (OUTBREAK) That’s how wars begin! (OUTBREAK of war),
17 Get up (‘get-up’ / style = DRESS-) with nearly all the characters in 10 across (nearly all ‘aged’ = -AGE) (DRESSAGE) for Arabian display, for example (Arabian/horse display, for example = DRESSAGE),
19 Detective (PI-) and judge (-RATE) (PIRATE) working overseas for Grace O’Malley (PIRATE Queen),
21 Took a cruise (SAILED) – is that what 6 down did? (‘pirate ship’ SAILED),
23 Some twenty per cent (some ‘twenTY Per cent’ = TYPE) work in the office (TYPE),
24 Market (SELL) what Belle Smith guarded (what ‘beLLE Smith’ = lles) bringing back (= reverse indicator) (lles = SELL).