Material dug up (5)
I believe the answer is:
denim
'material' is the definition.
(type of fabric)
'dug up' is the wordplay.
'dug' becomes 'mined' (dug into the ground).
'up' shows that the letters should be reversed in order (in down clue: letters go upwards).
'mined' backwards is 'DENIM'.
(Other definitions for denim that I've seen before include "dark blue material" , "Fabric used for jeans" , "Material for casual trousers or jackets" , "Mined (anag)" , "Coloured cotton twill" .)