Possible Clues:

• Bird enclosure placed for defending from retaliation
• Balanced reaction involving change of heart
• 'Measure for Measure' in full East-ender's headgear?
• Appropriate retaliation
• In kind
• Computing pro volunteers to cut off alcohol in revenge
• In annoyance, return bird, plump, having nothing right to eat
• Striking parity?
• Retaliation, when given the bird because of rubbish
• Keep at bird first in retaliation