Weapon knight stored in decorative fabric (5)
I believe the answer is:
lance
'weapon' is the definition.
(lance is a kind of weapon)
'knight stored in decorative fabric' is the wordplay.
'knight' becomes 'N' (chess abbreviation).
'stored in' is an insertion indicator.
'decorative fabric' becomes 'lace' (I've seen this in another clue).
'n' put within 'lace' is 'LANCE'.
(Other definitions for lance that I've seen before include "Cut open" , "Chap" , "Long, pointed weapon (5)." , "Boy - prick (a boil)" , "Pierce (a boil)" .)