Potbellied pet (3)
I believe the answer is:
pig
'potbellied pet' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for pig that I've seen before include "Domestic swine" , "& 16 Animal pen" , "Sow, perhaps" , "Boar or sow" , "Mass of metal simply cast" .)