Pub, heavy drinker (6)
I believe the answer is:
boozer
I believe this is a double definition.
'pub' is the first definition.
(boozer can informally mean a pub)
'heavy drinker' is the second definition.
(I've seen this before)
(Other definitions for boozer that I've seen before include "Inn" , "Heavy drinker" , "Pub (sl.)" , "Pub (slang)" .)