Returned coats in swindle (4)
I believe the answer is:
scam
'swindle' is the definition.
(scam is a kind of swindle)
'returned coats' is the wordplay.
'returned' says the letters should be written backwards.
'coats' becomes 'macs' (mac is a kind of coat).
'macs' backwards is 'SCAM'.
'in' acts as a link.
(Other definitions for scam that I've seen before include "Fraudulent trick or swindle" , "ploy" , "Rip off" , "Swindle (Slang)" , "Fraudulent business scheme" .)