Popular name for pub (3)
I believe the answer is:
inn
'for pub' is the definition.
(an inn is a type of pub)
'popular name' is the wordplay.
'popular' becomes 'in' ('in' can mean trendy).
'name' becomes 'n' (common abbreviation e.g. on forms).
'in'+'n'='INN'
(Other definitions for inn that I've seen before include "watering hole" , "Small hotel or country pub" , "Jamaica, for one" , "Hostelry, tavern" , "Pub providing food and accommodation" .)