Good artist following through with drug (6)
I believe the answer is:
viagra
'drug' is the definition.
(I have seen 'Potency drug ' mean 'viagra' so perhaps 'drug' could also mean 'viagra')
'good artist following through' is the wordplay.
'good' becomes 'g' (abbreviation).
'artist' becomes 'RA' (Royal Academician, member of Royal Academy of Arts).
'following' is a charade indicator (letters next to each other).
'through' becomes 'via' (I've seen this before).
'g'+'ra'='gra'
'gra' put after 'via' is 'VIAGRA'.
'with' is the link.
(Other definitions for viagra that I've seen before include "Promoter of the other" , "Sildenafil citrate" , "Controversial pills" , "potent drug?" , "Treatment" .)