Tolerate MDMA brought into boozer (4)
I believe the answer is:
bear
'tolerate' is the definition.
(synonyms)
'mdma brought into boozer' is the wordplay.
'mdma' becomes 'E' (MDMA is ecstasy, ie 'E').
'brought into' is an insertion indicator.
'boozer' becomes 'bar'.
'e' placed into 'bar' is 'BEAR'.
(Other definitions for bear that I've seen before include "stand" , "It may be polar or grizzly" , "stomach and > suffer" , "Put up with - beast!" , "Relating to charged particles" .)