Pub next to new outbuilding (4)
I believe the answer is:
barn
'outbuilding' is the definition.
(I've seen this before)
'pub next to new' is the wordplay.
'pub' becomes 'bar' (both are drinking establishments).
'next to' means one lot of letters go next to another.
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'bar'+'n'='BARN'
(Other definitions for barn that I've seen before include "Big building" , "Large outhouse" , "Bran stored in farm shed" , "Large farm outbuilding" , "Farm building for storing hay or grain" .)