Snoopy, to Charlie Brown (3)
I believe the answer is:
pet
'snoopy to charlie brown' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for pet that I've seen before include "Preferred" , "Paddy" , "House animal; sulk" , "The darling one in a small temper" , "Favourite, perhaps a domestic animal" .)