Fine material is used in sock? Not right (7)
I believe the answer is:
batiste
'fine material' is the definition.
(type of fine fabric)
'is used in sock? not right' is the wordplay.
'used in' is an insertion indicator.
'sock?' becomes 'batter' (both can mean to hit).
'not' indicates named letters should be taken away.
'right' becomes 'R' (common abbreviation).
'batter' with 'r' removed is 'batte'.
'is' put within 'batte' is 'BATISTE'.
(Other definitions for batiste that I've seen before include "Fine plain-weave cotton fabric" , "Set bait about to get a fine fabric" , "A very soft fine woven fabric" , "stuff" , "fine linen" .)