He dabbles in drugs, primarily with one of The Libertines (5)
I believe the answer is:
drake
'he dabbles' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how one could define the other.
'drugs primarily with one of the libertines' is the wordplay.
'primarily' indicates taking the first letters.
'with' means one lot of letters go next to another.
'one of the libertines' becomes 'rake' (I can't explain this - if you can you should believe this answer much more).
The initial letter of 'drugs' is 'd'.
'd'+'rake'='DRAKE'
'in' acts as a link.
Can you help me to learn more?
(Other definitions for drake that I've seen before include "sea captain" , "Male duck - circumnavigator" , "Ship" , "Male billed" , "Elizabethan favourite" .)