Don Corleone finally finished (4)
I believe the answer is:
done
'finished' is the definition.
(both can mean completed)
'don corleone finally' is the wordplay.
'finally' indicates one should take the final letters.
The final letter of 'corleone' is 'e'.
'don'+'e'='DONE'
(Other definitions for done that I've seen before include "This sort of thing is socially acceptable" , "See 23" , "Swindled" , "Managed" , "Performed" .)