Bird on tower decapitating rodent in retaliation (3,3,3)
I believe the answer is:
tit for tat
'in retaliation' is the definition.
(I've seen this before)
'bird on tower decapitating rodent' is the wordplay.
'bird' becomes 'tit' (tit is a kind of bird).
'on tower' becomes 'fort' (I am not sure about this - if you are sure you should believe this answer much more).
'decapitating' means to remove the first letter.
'rodent' becomes 'rat' (rat is a kind of rodent).
'rat' with its initial letter removed is 'at'.
'tit'+'fort'+'at'='TIT-FOR-TAT'
Can you help me to learn more?
(Other definitions for tit for tat that I've seen before include "Repayment in kind" , "... pork-pie maybe" , "You hit me, I hit you" , "An eye for an eye" , "Retaliation called for" .)