Daughter regularly taking ecstasy is finished (4)
I believe the answer is:
done
'is finished' is the definition.
(similar in meaning)
'daughter regularly taking ecstasy' is the wordplay.
'daughter' becomes 'd' (genealogical abbreviation).
'regularly taking' becomes 'on' (as in 'on drugs').
'ecstasy' becomes 'E' (informal term for the drug).
'd'+'on'+'e'='DONE'
(Other definitions for done that I've seen before include "(Of food) well cooked" , "Robbed" , "Swindled" , "Finished or ended" , "See 23" .)