Fleece coats from down under (4)
I believe the answer is:
scam
'fleece' is the definition.
(I've seen this in another clue)
'coats from down under' is the wordplay.
'coats' becomes 'macs' (mac is a kind of coat).
'from down under' shows that the letters should be reversed in order (in a down clue, letters written from bottom to top).
'macs' backwards is 'SCAM'.
(Other definitions for scam that I've seen before include "A modern kind of swindle" , "Rip-off" , "Fraudulent business scheme" , "fiddle" , "rook" .)