Soapstone makeup (4)
I believe the answer is:
talc
'soapstone makeup' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for talc that I've seen before include "soother" , "Cosmetic powder" , "(Mineral providing) powder" , "Bathroom powder (abbr)" , "Softest substance in Mohs scale of hardness" .)