Feline's naughty, as eats mice (7,3)
I believe the answer is:
siamese cat
'feline's' is the definition.
(Siamese cat is an example)
'naughty as eats mice' is the wordplay.
'naughty' is an anagram indicator.
'as'+'eats'+'mice'='aseatsmice'
'aseatsmice' anagrammed gives 'SIAMESE CAT'.
(Other definitions for siamese cat that I've seen before include "Elegant beast" , "Animal" , "Kitty" , "Feline breed" , "Domestic pet" .)