Possible Clues:

• Retaliation for an injury - almost equal
• Report of 19 shoddy items? Retaliation called for
• Equivalent retaliation
• You hit me, I hit you
• As the only difference, I must come in for a bit of retaliation
• Keep at bird first in retaliation
• Retaliation, when given the bird because of rubbish
• Striking parity?
• Appropriate retaliation
• 'Measure for Measure' in full East-ender's headgear?