Illegal drug of some potency (3)
I believe the answer is:
pot
This could be a double definition.
'illegal drug' is the first definition.
'pot' can be an answer for 'drug' (slang term for cannabis). I am unsure of the 'illegal' bit.
'some potency' is the second definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.
'of' acts as a link.
Can you help me to learn more?
(Other definitions for pot that I've seen before include "Cooking vessel, plant container and street drug" , "Somewhere to go" , "Sink (a snooker ball)" , "'A watched . . . never boils'" , "Storage container" .)