Clear old flame on Ecstasy charge (9)
I believe the answer is:
exonerate
'clear' is the definition.
(I've seen this before)
'old flame on ecstasy charge' is the wordplay.
'old flame' becomes 'ex' (I've seen this in other clues).
'ecstasy' becomes 'e' (informal term for the drug).
'charge' becomes 'rate' (rate is a kind of charge**).
'ex'+'on'+'e'+'rate'='EXONERATE'
(Other definitions for exonerate that I've seen before include "Clear of blame" , "Excuse" , "Pronounce not guilty of a crime" , "Acquit" , "Free from obligation, blame" .)