Woolly coat (6)
(Other definitions for sheepskin that I've seen before include "Woolly pelt" , "Ovine outer layer used in coats and rugs" , "leather" , "coat" , "Fleece garment" .)
'woolly coat' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for fleece that I've seen before include "winter coat" , "Woolly hair of sheep" , "Sheepskin - rook" , "Cheat" , "Gull" .)