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' means one lot of letters goes inside another.
'an unusual' is an anagram indicator.
'soft' becomes 'p' (musical abbreviation for 'piano').
'case' is an anagram of '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" .)