Sable's skin idiot keeps in cupboard (6)
I believe the answer is:
closet
'cupboard' is the definition.
(synonyms)
'sable's skin idiot keeps' is the wordplay.
'skin' says to hollow out the word (remove centre letters).
'idiot' becomes 'clot' (I've seen this in other clues).
'keeps' means one lot of letters goes inside another (inserted letters are kept inside).
'sable' with its centre taken out is 'se'.
'se' placed inside 'clot' is 'CLOSET'.
'in' acts as a link.
(Other definitions for closet that I've seen before include "Tall cupboard, wardrobe" , "Furtive" , "Cupboard (to come out of)" , "North American cupboard" , "American cupboard or wardrobe" .)