Wife, healthy swimmer with lots of blubber! (5)
I believe the answer is:
whale
'swimmer with lots of blubber' is the definition.
I can't judge whether this defines the answer.
'wife healthy' is the wordplay.
'wife' becomes 'w' (abbreviation).
'healthy' becomes 'hale' (hale can mean fit and healthy).
'w'+'hale'='WHALE'
Can you help me to learn more?
(Other definitions for whale that I've seen before include "It breathes through a blowhole" , "Mammoth marine mammal" , "monster" , "Largest animal" , "Large marine creature" .)