Pub swinger? (3,4)
I believe the answer is:
inn sign
'pub swinger?' is the definition.
I know nothing about this answer so I cannot tell whether this works.
'pub swinger?' is the wordplay.
'pub' becomes 'inn' (an inn is a type of pub).
'swinger?' becomes 'sign' (I am not sure about this - if you are sure you should believe this answer much more).
'inn'+'sign'='INN-SIGN'
Can you help me to learn more?
(Other definitions for inn sign that I've seen before include "one shows identity at pub door" , "Pub name carrier" , ""The Bull" perhaps" , "Board outside a pub" , "Board showing name of pub" .)