Small role (5)
I believe the answer is:
cameo
'small role' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for cameo that I've seen before include "E. Med. nation" , "Star's tiny role" , "Item of jewellery with a portrait - distinguished actor's minor role" , "Carving in low relief" , "Carving in relief, on a brooch say" .)