Material in overall use (5)
I believe the answer is:
denim
'material' is the definition.
(type of fabric)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for denim that I've seen before include "Material for casual trousers or jackets" , "Fabric used for jeans" , "Durable material" , "Mined (anag)" , "maker of jeans" .)