Mined material? (5)
I believe the answer is:
denim
'mined material?' is the definition.
'denim' can be an answer for 'material?' (denim is a kind of material). I am not sure about the 'mined' bit.
'mined material?' is the wordplay.
'material?' indicates anagramming the letters (I've seen 'material' mean this (the letters provide the material for a new word)).
'mined' is an anagram of 'DENIM'.
Can you help me to learn more?
(Other definitions for denim that I've seen before include "Cotton twill fabric" , "maker of jeans" , "Coarse durable twill-weave cotton fabric" , "Hard-wearing cloth" , "Tough cotton fabric" .)