Tax-deferred plan (3)
I believe the answer is:
ira
'tax-deferred 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 "Militant Irish nationalist organisation" , "terrorists" , "Illegal organisation, initially" , "Illegal organisation, in short" , "Brother of George Gershwin" .)