Shut in some forgotten closet (7)
I believe the answer is:
enclose
'shut in' is the definition.
(synonyms)
'some forgotten closet' is the wordplay.
'some' says the answer is hidden in the clue (some parts of the word are used).
'ENCLOSE' can be found hidden inside 'forgotten closet'.
(Other definitions for enclose that I've seen before include "Surround on all sides" , "Surround, envelop" , "Bound" , "embrace" , "Include N pen" .)