Contented kitty's sound (4)
I believe the answer is:
purr
'contented kitty's sound' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for purr that I've seen before include "Sound like happy cat" , "Sound of a happy mog" , "Cat's contented sound" , "content? I might" , "Sound of contentment" .)