It may be smoked out of its den (5)
I believe the answer is:
opium
This might be a double definition.
'it may be smoked out of its' is the first definition.
The definition suggests a singular noun which matches the answer.
'den' is the second definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Maybe you can see an association between them that I don't see?
Can you help me to learn more?
(Other definitions for opium that I've seen before include "Derivative of Poppy" , "Poppy-based drug" , "wars with China" , "The stuff of wars" , "justification for war once?" .)