Fiddle about during kinky sex (4)
I believe the answer is:
scam
'fiddle' is the definition.
(I've seen this before)
'about during kinky sex' is the wordplay.
'about' becomes 'ca' (abbreviation for 'circa').
'during' means one lot of letters goes inside another.
'kinky sex' becomes 'sm' (I've seen this in other clues).
'ca' inserted within 'sm' is 'SCAM'.
(Other definitions for scam that I've seen before include "Fraudulent scheme, swindle" , "Fraudulent trick or swindle" , "'A con, deception (4)'" , "Screw" , "A modern kind of swindle" .)