Bar welcomes large group drooling (9)
I believe the answer is:
slavering
'drooling' is the definition.
('slaver' can be a synonym of 'drool')
'bar welcomes large group' is the wordplay.
'bar welcomes large' becomes 'slave' (I am not sure about this - if you are sure you should believe this answer much more).
'group' becomes 'ring' (a ring is a criminal organisation).
'slave'+'ring'='SLAVERING'
Can you help me to learn more?
(Other definitions for slavering that I've seen before include "Desperately keen" , "be desperately anxious" , "Drooling" .)