Does such mining have its seamy side? (4)
I believe the answer is:
coal
'side?' is the definition.
The answer and definition can be both natural objects as well as being singular nouns.
Maybe you can see a link between them that I don't see?
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for coal that I've seen before include "Solid fuel" , "slack" , "Carbonaceous rock used as fuel" , "Three domestic fuels" , "Mined fuel" .)