Cosmetic for cheek used by staff (8)
I believe the answer is:
lipstick
'cosmetic' is the definition.
(I know that lipstick is a type of make-up)
'cheek used by staff' is the wordplay.
'cheek' becomes 'lip' (both can mean insolence or rudeness).
'used by' means one lot of letters go next to another.
'staff' becomes 'stick' (I've seen this before).
'lip'+'stick'='LIPSTICK'
'for' is the link.
(Other definitions for lipstick that I've seen before include "Mouth paint?" , "Cosmetic item" , "offered to one's face" , "Cosmetic used to colour around the mouth" , "Type of paint" .)