Possible Clues:

• Where there's little escape from current ebbing through broken bridge
• Enclosure for a canary, eg
• Small aviary
• Local prison has bars for a little chat perhaps
• Enclosure for a budgie, say
• What may restrict Polly's walk in London
• A walk from prison to prison
• Where chirpy creatures may well be seen behind bars
• Fliers' accommodation with bars
• An environment that's very limiting for flight or walk