Kitty's wrongful act (3)
I believe the answer is:
cat
'kitty's' is the definition.
(thesaurus)
'wrongful act' is the wordplay.
'wrongful' indicates anagramming the letters (I've seen this in other clues).
'act' anagrammed gives 'CAT'.
(Other definitions for cat that I've seen before include "Eg, tiger, lion" , "Feline - whip" , "Lash < jazz fan" , "Sailor's whip with nine knotted strands" , "Tiger, for instance" .)