Small acting part (5)
I believe the answer is:
cameo
'small acting part' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for cameo that I've seen before include "Miniature picture" , "Small acting role; item of jewellery" , "Carving in relief, on a brooch say" , "Brooch with an engraving in low relief" , "Piece of jewellery with carved portrait" .)