Purring animal (3)
I believe the answer is:
cat
'purring animal' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for cat that I've seen before include "Feline mammal" , "Feline mammel" , "Domestic animal" , "eg Leopard" , "one's pyjamas? They're an excellent thing" .)