No 12099, Wednesday 30 Aug 2017, Arden

ACROSS
9   Come forward with scheme (7) PROJECT [DD]
10 Kill and annex large country (7) ICELAND {ICE}{L}{AND}

11 Drunk retains wine (7) RETSINA*
12 Boeing design includes long base (7) IGNOBLE {L} in {BOEING}*
13 Order is a nice one, missing submission (9) OBEISANCE {OBE}{IS}{A}{NiCE}
15 Finally cabbage goes into head of cauliflower and salted (5) CURED {c...gE} in {CURD}
16 As per law, binding on one's associate (7) LEGALLY {LEG}{ALLY} Anno for LEG pending See comments :-)
19 Trained to agree on the mission (4,3) TOOK AIM {TO}{OK} {AIM}
20 Have lumps inside the soft palate (5) VELUM [T]

21 Very small but a negative cryptic clue (9) MINUSCULE {MINUS}{CLUE*} Didn't know of this variant spelling See comments
25 Following on money, used regularly (7) RETINUE {RE}{TIN}{UsEd}
26 Endless choice, like so many of his paintings (7) PICASSO {PICk}{AS}{SO} Semi&lit

28 Birds took on westbound Columbus, perhaps (7) GENOESE {GE{ON<=}ESE}
29 Nearly gone, taking hundred by stealth (7) LARCENY {C} in {NEARLY}* By stealth? See comments

DOWN
1   Old wine, only here in European city (6) OPORTO {O}{PORT}{O}
2   Perhaps David's taken it up round his neck (3,3) BOW TIE  {IT<=} in {BOWE}
3   Food shipment reduced by 50% (4) DELI DELIvery
4   A kind of exertion (6) STRAIN [DD]
5   Hard working man, chasing capital (8) DILIGENT {DILI}{GENT}
6   Maybe precious metal is hoarded — extremely harmful (10) PERNICIOUS {NI} in {PRECIOUS}*
7   Possible terrain in the centre of the capital (8) CANBERRA {CAN BE}{teRRAin}
8   Supplement on lace curtains, basically clumsy (8) ADDENDUM {ADD}{END}{clUMsy}
14 Arsenal mad to play poker (10) SALAMANDER*
16 "Purchase large rum bottles, girl" (8) LEVERAGE {EVE} in {LARGE}*
17 Explosive language used in exclamation (8) GELATINE {LATIN} in {GEE}
18 Howled at setter in dreamy, confused state (8) YAMMERED {ME} in {DREAMY}*
22 Staff getting round up on weapon (6) NAPALM {M{LAP}AN}<=
23 Bad result in Northern Ireland (6) ULSTER*
24 Making money gets first priority — an example is Washington (6) EPONYM {Pr...y} in {MONEY}*
27 Complain about the missing picture on the mat (4) CARP CARPet

GRID