Clue: Provider of polish, a grotesque comedian? (5)
Answer: EMERY
Explanation: Definition: Provider of polish
Double definition, one relating to an emery cloth, the second to Dick Emery (1915-83), a British comedian who appeared in an eponymous TV show. 
 
 
*I'm not sure about the "grotesque" bit – he wasn't particularly ugly and his comedy was no more shocking than many others…