Do talk about Ecstasy (5)
I believe the answer is:
cheat
'do' is the definition.
(thesaurus)
'talk about ecstasy' is the wordplay.
'talk' becomes 'chat' (I've seen this before**).
'about' is an insertion indicator.
'ecstasy' becomes 'e' (informal term for the drug).
'chat' enclosing 'e' is 'CHEAT'.
(Other definitions for cheat that I've seen before include "Compete dishonestly" , "Deceive, defraud" , "offending pupil" , "Play false" , "Trick or swindle" .)