Obtain advantage over scoundrel with ecstasy (7)
I believe the answer is:
procure
'obtain' is the definition.
(I've seen this before)
'advantage over scoundrel with ecstasy' is the wordplay.
'advantage' becomes 'pro' (as in pros and cons).
'over' says to put letters next to each other.
'scoundrel' becomes 'cur' (I've seen this before**).
'with' says to put letters next to each other.
'ecstasy' becomes 'e' (informal term for the drug).
'pro'+'cur'+'e'='PROCURE'
(Other definitions for procure that I've seen before include "Acquire" , "Obtain; solicit" , "Get by special effort" .)