Takes drug endlessly (3)
I believe the answer is:
has
'takes' is the definition.
('have' can be a synonym of 'take')
'drug endlessly' is the wordplay.
'drug' becomes 'hash' (hash is a kind of drug).
'endlessly' means to remove the last letter.
'hash' with its final letter taken off is 'HAS'.
(Other definitions for has that I've seen before include "Possesses or owns" , "Eats" , "Bears" , "Owns, holds" , "suffers from" .)