Not quite a royal family (3)
I believe the answer is:
kin
'family' is the definition.
('kin' can be a synonym of 'family')
'not quite a royal' is the wordplay.
'not quite' means to remove the last letter.
'a royal' becomes 'king' (I've seen this before).
'king' with its final letter taken away is 'KIN'.
(Other definitions for kin that I've seen before include "Flesh and blood" , "Connections; family" , "Group of relations" , "Family and relations" , "A person's relatives, goes with kith" .)