Wounding monarch for holding back piece of fish (7)
I believe the answer is:
knifing
'wounding monarch for holding back piece of fish' is the definition.
I can't tell whether this defines the answer.
'for holding back piece of fish' is the wordplay.
'for' becomes 'king' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'holding' is an insertion indicator.
'back' is a reversal indicator.
'piece of fish' becomes 'fin' (fish have fins).
'fin' in reverse letter order is 'nif'.
'king' going around 'nif' is 'KNIFING'.
Can you help me to learn more?
(Other definitions for knifing that I've seen before include "Sticking" , "An attack involving a sharp blade" , "Violent incident involving a sharp weapon" .)