Provider of polish, a grotesque comedian? (5)
I believe the answer is:
emery
I believe this clue is a double definition.
'provider of polish' is the first definition.
(emery paper may be used to polish something)
'a grotesque comedian?' is the second definition.
(Dick Emery often played grotesque characters)
(Other definitions for emery that I've seen before include "Abrasive form of corundum" , "Abrasive material" , "Hard grey-black mineral used as an abrasive" , "Black abrasive" , "Coating on paper used as an abrasive" .)