Considered overall, it's tough stuff (5)
I believe the answer is:
denim
This clue could be a double definition.
'considered overall' is the first definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Perhaps there's an association between them I don't understand?
'tough stuff' is the second definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'it's' acts as a link.
Can you help me to learn more?
(Other definitions for denim that I've seen before include "Hard-wearing cloth" , "Cotton twill fabric" , "Thick cotton cloth" , "Mined (anag)" , "Hard-wearing blue fabric" .)