A woven fabric to suit oneself (2,4)
I believe the answer is:
at will
'to suit oneself' is the definition.
(I've seen this in another clue)
'a woven fabric' is the wordplay.
'woven fabric' becomes 'twill' (I've seen this before).
'a'+'twill'='AT WILL'
(Other definitions for at will that I've seen before include "when one wants" , "Whenever one pleases, say fire rifle" , "take it as I please" , "Whenever you please, as you like" , "When I choose" .)