Supply ecstasy and crack (5)
I believe the answer is:
equip
'supply' is the definition.
(I know that equip is a more specific form of supply)
'ecstasy and crack' is the wordplay.
'ecstasy' becomes 'E' (informal term for the drug).
'and' says to put letters next to each other.
'crack' becomes 'quip' (both can mean a joke).
'e'+'quip'='EQUIP'
(Other definitions for equip that I've seen before include "Fit out, supply" , "Provide with items (for particular task)" , "Sally" , "Outfit" , "Provide with kit" .)