Mac to use moisturiser (7)
I believe the answer is:
oilskin
'mac' is the definition.
(oilskin is a type of raincoat or macintosh)
I can't explain the remainder of the clue.
(Other definitions for oilskin that I've seen before include "protection for Ainslie?" , "material" , "Heavy waterproofed cloth" , "Protective coat" , "Waterproof cloth for rain-gear" .)