With Ecstasy gone, supply crack (4)
I believe the answer is:
quip
'crack' is the definition.
(both can mean a joke)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for quip that I've seen before include "Brief witty saying" , "West African country" , "Bon mot" , "Smart remark" , "Part of the psyche" .)