Material exploited the wrong way (5)
I believe the answer is:
denim
'material' is the definition.
(denim is a kind of material)
'exploited the wrong way' is the wordplay.
'exploited' becomes 'mined' (mining is a kind of exploiting).
'the wrong way' says the letters should be written backwards.
'mined' reversed gives 'DENIM'.
(Other definitions for denim that I've seen before include "Hard-wearing cloth" , "Thick cotton cloth" , "maker of jeans" , "Material for casual trousers or jackets" , "Durable material" .)