Songbird allowed to circle pub (6)
I believe the answer is:
linnet
'songbird' is the definition.
(I've seen this before)
'allowed to circle pub' is the wordplay.
'allowed' becomes 'let' (I've seen this before).
'to circle' is an insertion indicator.
'pub' becomes 'inn' (I've seen this before).
'let' going around 'inn' is 'LINNET'.
(Other definitions for linnet that I've seen before include "Brown-gray kind of finch" , "Passerine bird" , "Songbird (to 6 18)" , "Singer" , "Winger" .)