Rip off sheep's clothing (6)
I believe the answer is:
fleece
I believe this is a double definition.
'rip off' is the first definition.
(I know that fleece is a kind of rip off)
'sheep's clothing' is the second definition.
(Other definitions for fleece that I've seen before include "A sheep's woolly coat" , "Woolly coat of a sheep" , "Rook; animal's coat" , "Charge too much" , "Woollen coat of sheep" .)