Across
Starts off one risky transaction in black, ready to divide into groups (8)
I haven't cracked this one yet — but Fifteensquared have:
starting letters from O-[ne] R-[isky] T-[ransaction]; all inside SABLE="black"
Cardinal recently appointed black or white bishop, say (6)
Most tragic need in defeat (8)
Manipulate position after white’s opening (6)
One who sits obsessively writing letters in square (9,6)
Some players’ forte, oddly – its key components are black and white (5)
Old district that’s frequently created 20 (2,3)
I haven't cracked this one yet — but Fifteensquared have:
definition: Op art is a style of art that often uses black and white [wiki] O (Old) + PART="district"
Home sides in some games recorded on paper (2,5,3,5)
American rock-and-roller’s piece to play, combining two numbers (6)
Male joining females in white, typically, in part of Scotland (8)
Black bird that transported Darwin (6)
Problem for plant that could be why I left (8)
Down
Black headgear for some cops and some cricketers (7)
Statuesque sheep, for example, all the same? (5-5)
Starters for All Blacks look extremely talented (4)
Movie with traditionally distinctive headgear we back (7)
Like Mont Blanc, with cow wandering into shot (4-6)
I haven't cracked this one yet — but Fifteensquared have:
anagram/"wandering" of (cow)*, inside SNAPPED=took a photo="shot"
Singular white bird that’s rarely black (4)
Hard cheese dished up initially with black spread (3,4)
I haven't cracked this one yet — but Fifteensquared have:
definition: 'hard cheese' is an expression used to mean 'tough luck' anagram/"spread" of ( d u black)*, with d u from the initials of d -[ished] u -[p]
White container we put outside in prison (4,6)
I haven't cracked this one yet — but Fifteensquared have:
definition: a container for whites [white wines] WE (from surface), put around IN (from surface); plus COOLER=slang for "prison"
Like Labrador, as opposed to 5? (4-6)
I haven't cracked this one yet — but Fifteensquared have:
as opposed to being white-haired / SNOW-CAPPED (5dn)
Game which ends with white dispatching black (7)
I haven't cracked this one yet — but Fifteensquared have:
in a game of snooker where all balls are potted, the black ball would be the last ball potted (using the white cue ball)
Gets ready for gathering in white nuts (7)
I haven't cracked this one yet — but Fifteensquared have:
CASHES=gets/gives cash for [e.g. a cheque]="Gets ready for", with "ready" as slang for cash; around W (white)
Play game for two (7)
I advance after securing a major role in 19 (4)
Vivacity of performance in part of noir blockbuster elevated (4)
Type letters or click words in the clue