Apple of one's eye (3)
I believe the answer is:
pet
'apple of one's eye' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for pet that I've seen before include "Caress - budgie, perhaps?" , "Cat or dog" , "Domesticated animal" , "Little darling" , "Tamed domestic animal" .)