Small cupboard (6)
I believe the answer is:
closet
'small cupboard' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for closet that I've seen before include "A small room - best to come out of it" , "American cupboard or wardrobe" , "secret is revealed" , "Private room; cupboard" , "Wardrobe in the US" .)