Finch allowed to circle pub (6)
I believe the answer is:
linnet
'finch' is the definition.
(linnet is a kind of finch)
'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' placed around 'inn' is 'LINNET'.
(Other definitions for linnet that I've seen before include "Yeats's song-bird" , "House finch" , "North London terminus" , "Songbird (to 6 18)" , "Bird in the finch family" .)