Arkin of "Argo" (4)
I believe the answer is:
alan
'arkin of argo' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for alan that I've seen before include "-- Sugar, British entrepreneur" , "Boy's name" , "Lana (anag.), man's name" , "- Bates, - Bennett" , "Boy" .)