Ordered wrong drug (4)
I believe the answer is:
bade
'ordered' is the definition.
(past tense of 'bid' as in to order)
'wrong drug' is the wordplay.
'wrong' becomes 'bad' ().
'drug' becomes 'e' (E is another name for ecstasy).
'bad'+'e'='BADE'
(Other definitions for bade that I've seen before include "Ordered" , "Commanded with bead" , "Invited" .)