No 11580, Monday 21 Dec 2015, Incognito

I'm seeing and hearing double today. I wonder if it's the effect of the drinks at the celebrations over the last three days with the Madras Sappers!!!

ACROSS
8   Indian uncle's American mother (4) MAMA [DD]
9   Reckless auction endlessly rigged in India and the States (10) INCAUTIOUS {AUCTIOn}* in {IN}{US}
10 Child goes back twice to antelope (3-3) DIK-DIK <=

11 He croons around boat (8) SCHOONER*
12 Arab boor toured Pacific island (4,4) BORA BORA*
14 After turn, one pot is returned to a fabulous island (6) UTOPIA {U}{TOP}{1}<={A}
16 Planter’s stake (4) ANTE [T]
17 Lucifer's game (5) MATCH [DD]
18 Remove from operation theatre in America? Quite the opposite! (4) OUST {O{US}T}
19 Tintin's dance? (6) CANCAN {CAN}{CAN}

21 Goodbye toast (4-4) CHIP-CHIP [DD] From 'Goodbye Mr Chips'? (Addendum - CHIN-CHIN [DD] - See comments)
23 A rag is returned by chief with money for some gelatinous substance (4-4) AGAR-AGAR {A}{GAR<=} {AGA}{R}
26 Kolkata's airport area’s forbidden ordnance (3,3) DUM DUM [DD]
27 Kenyan conservation area's non-government organisation gets royal order twice (10) NGORONGORO {NGO}{R}{O} x 2 How do we pronounce that!
28 Hear about bird (4) RHEA*

DOWN
1   Carolina, if reformed can become The Golden State (10) CALIFORNIA*
2   Cobra's enemy's plant (8) MANDRAKE [DD]
3   Going around with king, leads to maidenhair tree (6) GINKGO {K} in {GOING}*

4   Broken case for top cards (4) ACES*
5   Quiet! Quiet! It's top secret! (4-4) HUSH-HUSH {HUSH}-{HUSH}
6   Male escort initially got a girl and open lips osculation for starters (6) GIGOLO {Got}{1}{G} {Open}{Lips}{Os...n}
7   Greek letter carried by the French animal (4) MULE {MU}{LE}
13 Funny act has funny action after dropping an egg (5) ANTIC ACTIoN*
15 Starts educational establishments (10) INSTITUTES [DD]
17 Adam, for example, is getting on and running (8) MANAGING {MAN}{AGING}
18 Encore — danced around Missouri again (4,4) ONCE MORE {MO} in {ENCORE}*
20 Relieve from disease using a red poison (6) CURARE {CUR{A}{R}E}
22 No radio broadcast without primary antenna inside (6) INDOOR {NO+RaDIO}*
24 Legal officer in Georgia is mad (4) GAGA {AG} in {GA}
25 Othello, perhaps, returned to living area (4) ROOM <=

GRID