Wife heartlessly walloping fish (7)
I believe the answer is:
whiting
'fish' is the definition.
(whiting is a kind of fish)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for whiting that I've seen before include "[SOMETHING FISHY]" , "Small fish related to cod" , "Edible marine fish" , "Small sea fish or ground chalk for painting" , "North Atlantic food fish" .)