Don's family (4,6)
I believe the answer is:
cosa nostra
'don's family' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for cosa nostra that I've seen before include "Criminals" , "US crime syndicate with links to the Mafia" , "The Mob" , "Criminal element" , "criminal US group" .)