Racecourse punters not exploited yet (9)
I believe the answer is:
newmarket
'racecourse' is the definition.
(I've seen this before)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for newmarket that I've seen before include "Racecourse - card game" , "Racing town" , "horse-racing centre" , "course?" , "Betting card came" .)