Family adoptee (3)
I believe the answer is:
pet
'family adoptee' 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 "The darling one in a small temper" , "Tamed animal; sulk" , "Cherished animal" , "Cherished favourite" , "Favourite, may be teacher's" .)