Entreat a different animal (8)
I believe the answer is:
anteater
'animal' is the definition.
(anteater is a kind of animal)
'entreat a different' is the wordplay.
'different' indicates an anagram (letters placed in a different order).
'entreat'+'a'='entreata'
'entreata' with letters rearranged gives 'ANTEATER'.
(Other definitions for anteater that I've seen before include "animal (this one?)" , "Scaly insectivore" , "soldiers killed by this?" , "Long-snouted insectivore" , "Insect consumer" .)