The stuff ingeniously mined (5)
I believe the answer is:
denim
'the stuff' is the definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Maybe you can see a link between them that I don't see?
'ingeniously mined' is the wordplay.
'ingeniously' indicates an anagram (I've seen this in other clues).
'mined' with letters rearranged gives 'DENIM'.
Can you help me to learn more?
(Other definitions for denim that I've seen before include "Coarse durable twill-weave cotton fabric" , "Cotton twill fabric" , "maker of jeans" , "Material for casual trousers or jackets" , "Hard-wearing cotton fabric" .)