Drug’s stolen by marksman? (5,4)
I believe the answer is:
crack shot
'marksman?' is the definition.
('crack shot' can be a synonym of 'marksman')
'drug's stolen by' is the wordplay.
'drug's' becomes 'cracks' (crack is a kind of drug).
'stolen' becomes 'hot' (stolen goods are 'hot').
'by' says to put letters next to each other.
'cracks'+'hot'='CRACK SHOT'
(Other definitions for crack shot that I've seen before include "Expert marksman" , "Ace marksman" .)