Allow to cage a local bird (6)
I believe the answer is:
linnet
'bird' is the definition.
(linnet is a kind of bird)
'allow to cage a local' is the wordplay.
'allow' becomes 'let' (synonyms).
'to cage' means one lot of letters goes inside another (inserted letters are locked up).
'a local' becomes 'inn' (local can mean someone's local pub).
'let' placed around 'inn' is 'LINNET'.
(Other definitions for linnet that I've seen before include "Brown-gray kind of finch" , "Songbird in Lent" , "Finch formerly popular as a pet" , "Finch so named because it feeds on flax" , "Small finch, once popular as a caged songbird" .)