Chalky powder (4)
I believe the answer is:
talc
'chalky 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 "It is used to absorb moisture" , "Mica - scented body powder" , "Softest mineral on Mohs hardness scale" , "Scented powder used after bathing" , "White powder for the bathroom" .)