Cat not in life nine, frisky (6)
I believe the answer is:
feline
'cat' is the definition.
(thesaurus)
'not in life nine frisky' is the wordplay.
'not' is a deletion indicator.
'frisky' indicates anagramming the letters.
'life'+'nine'='lifenine'
'lifenine' with 'in' removed is 'lifene'.
'lifene' anagrammed gives 'FELINE'.
(Other definitions for feline that I've seen before include "16 [TOM] perhaps" , "Mog" , "Like a cat" , "Persian for one" , "Relating to cats" .)