Whip a pet (3)
I believe the answer is:
I believe this is a double definition.
'whip' is the first definition.
(cat o' nine tails, cat for short is a type of whip)
'a pet' is the second definition.
(cats are often kept as pets)
(Other definitions for cat that I've seen before include "Lash < jazz fan" , "Tabby" , "See 23" , "Animal - one with nine tails!" , "one's pyjamas? They're an excellent thing" .)