Cheek cosmetic (5)
I believe the answer is:
rouge
'cheek cosmetic' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for rouge that I've seen before include "Blusher" , "Red cosmetic to colour cheeks" , "Reddish cosmetic for colouring cheeks" , "Rumpled, disordered" , "Ferric oxide powder" .)