"Traditional" plan (3)
I believe the answer is:
ira
'traditional plan' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for ira that I've seen before include "Brother of George Gershwin" , "Songwriter George's elder brother" , "nationalists" , "Gershwin, say" , "Militant Irish nationalist organisation" .)