Somehow mined for material (5)
I believe the answer is:
denim
'for material' is the definition.
(type of fabric)
'somehow mined' is the wordplay.
'somehow' is an anagram indicator.
'mined' with letters rearranged gives 'DENIM'.
(Other definitions for denim that I've seen before include "Coloured cotton twill" , "Hard-wearing cotton fabric" , "Material for casual trousers or jackets" , "Hard-wearing blue fabric" , "Durable material" .)