Popular northern hostelry (3)
I believe the answer is:
inn
'hostelry' is the definition.
('inn' can be a synonym of 'hostelry')
'popular northern' is the wordplay.
'popular' becomes 'in'.
'northern' becomes 'n' (abbreviation e.g. N. Ireland).
'in'+'n'='INN'
(Other definitions for inn that I've seen before include "Hotel or public house" , "Hostelry, tavern" , "One of Lincoln's" , "eg the Tabard" , "It provides rest for the traveller" .)