Favourite cat, say (3)
I believe the answer is:
pet
This clue is a double definition.
'favourite' is the first definition.
(synonyms)
'cat say' is the second definition.
(cats are kept as pets)
(Other definitions for pet that I've seen before include "Favourite, darling" , "Favoured child or animal" , "Cherished animal" , "Caress - budgie, perhaps?" , "Particular favourite" .)