Post-shower powder (4)
I believe the answer is:
talc
'post-shower powder' 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 "After-bath powder" , "Soft white powder" , "Drier" , "It is used to absorb moisture" , "Softest mineral on Mohs hardness scale" .)