Bunco (4)
I believe the answer is:
scam
'bunco' is the definition.
(I know that bunco can be written as scam)
This is all the clue.
(Other definitions for scam that I've seen before include "fiddle" , "Fraud, trick (slang)" , "Swindle (Slang)" , "'A con, deception (4)'" , "Rip off" .)