Ripoff (4)
I believe the answer is:
scam
'ripoff' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for scam that I've seen before include "'A con, deception (4)'" , "Swindle (sl.)" , "Fraudulent business scheme" , "Fraud, trick (slang)" , "A modern kind of swindle" .)