No 12097, Monday 28 Aug 2017, Arden

ACROSS
1   Pain goes away after winner gets the cake (8,6) VICTORIA SPONGE {VICTOR}{PAIN+GOES}*

10 Ship's engine part (5) LINER [DD]
11 Resolve to become a President (9) ROOSEVELT*
12 Give it up, offer it in other words (7) FORFEIT*
13 Additional measure taken to reach the farthest points (7) EXTREMA {EXTR{EM}A}
14 Composed hymn about poise of a young woman (5) NYMPH {NYM{P}H*}
16 Born on the day one goes for full replacement necessarily (9) NEEDFULLY {NEE}{D(-a+full)FULLY}
19 Breaking a bond and drinking wine — it’s torture (9) BASTINADO {ASTI} in {A+BOND}*
20 Stick to the law always (5) LEVER {L}{EVER}
22 Players have one in and one out of the game (7) CANASTA {C{AN}AST}{A}
25 Criminal goes outside to bug secret police (7) GESTAPO {GOES}* over {TAP}
27 Cow's wet, one goes to rock bottom (9) LOWERMOST {LOWER}{MOiST}
28 Colour touch — horse has it regularly (5) OCHRE {tOuCh+hOrSe}
29 Spooner’s happy, looking at cheating at the polls (14) GERRYMANDERING {(-m+g)GERRY}{(-g+m)MANDERING}

DOWN
2   It maybe amusing to have a choice, but he doesn't know (9) IGNORAMUS {AMUSING}* over {OR}
3   Brief stay in Battersea (5) TERSE [T]
4   Indian businessman takes train, travels to a mythical place (9) RURITANIA {RUIA} over {TRAIN}*
5   Repent when you have lunch (5) ATONE {AT}{ONE}
6   Fill up ten fragments, they're more than enough (9) PLENTIFUL*
7   She’s relatively fine, taking drug (5) NIECE {NI{E}CE}
8   A true story about missing a peak for a creek (7) ESTUARY {A+TRUE+StorY}*
9   Organic compound busy protecting life forms (6) OLEFIN {ON} over {LIFE}*
15 Heard beneficiaries' appeal to keep the locks in place (4,5) HAIR SPRAY (~ heirs){HAIRS}{PRAY}
17 Happy to hold on, good when stretched (9) ELONGATED {EL{ON}{G}ATED}
18 Large built, have it with an even larger monstrosity (9) LEVIATHAN {L}{HAVE+IT}*{AN}
19 Support Indian people, work pending (7) BACKLOG {BACK}{LOG}
21 Ways to be heard in Greece (6) RHODES (~roads)
23 Post changed hands, it's relatively recent (5) NEWER NEWE(-l+r)R
24 Possibly no-go-area, one avoided the old market (5) AGORA {no-GO-AReA}*
26 Look minutely for Carbon in an acidic environment (5) SCOUR {S{C}OUR}

GRID