Material for jeans (5)
I believe the answer is:
denim
'material for jeans' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for denim that I've seen before include "Hard-wearing material seen in jeans" , "Hard-wearing cotton fabric" , "Hard-wearing cloth" , "Hard-wearing clothing material, twilled cotton" , "Fabric used for jeans" .)