Fellow covering limb in item of clothing (7)
I believe the answer is:
garment
'item of clothing' is the definition.
(I've seen this before)
'fellow covering limb' is the wordplay.
'fellow' becomes 'gent' (synonyms).
'covering' means one lot of letters goes inside another.
'limb' becomes 'arm' (arm is a kind of limb).
'gent' enclosing 'arm' is 'GARMENT'.
'in' is the link.
(Other definitions for garment that I've seen before include "Something put on" , "Grant me (anag.)" , "Item of clothing" , "An article of clothing (7)" , "Raiment" .)