In an unusual case, soft garments (5)
I believe the answer is:
capes
'garments' is the definition.
(cape is a kind of garment)
'in an unusual case soft' is the wordplay.
'in' is an insertion indicator.
'an unusual' indicates an anagram.
'soft' becomes 'p' (musical abbreviation for 'piano').
'case' anagrammed gives 'caes'.
'caes' enclosing 'p' is 'CAPES'.
(Other definitions for capes that I've seen before include "Cloaks or headlands" , "Space for cloaks" , "Short cloaks" , "may be worn" , "Sleeveless cloaks - promontories" .)