American queen is drug taker (4)
I believe the answer is:
user
'drug taker' is the definition.
(I've seen this before)
'american queen' is the wordplay.
'american' becomes 'us'.
'queen' becomes 'er' (abbreviation for Elizabeth Regina).
'us'+'er'='USER'
'is' is the link.
(Other definitions for user that I've seen before include "Drug-taker" , "Druggie" , "Consumer" , "One who exploits, to be sure" , "Person who takes drugs" .)