Aviator and wife get healthy cetacean (5,5)
I believe the answer is:
pilot whale
'cetacean' is the definition.
(I know that pilot whale is a type of dolphin)
'aviator and wife get healthy' is the wordplay.
'aviator' becomes 'pilot' (pilot is a kind of aviator).
'and' is a charade indicator (letters next to each other).
'wife' becomes 'w' (abbreviation).
'get' is a charade indicator (letters next to each other).
'healthy' becomes 'hale' (hale can mean fit and healthy).
'pilot'+'w'+'hale'='PILOT WHALE'
(Other definitions for pilot whale that I've seen before include "Blackfish" , "squid eater" .)