Investment initials (3)
I believe the answer is:
ira
'investment initials' 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 "Illegal organisation, initially" , "Militant republicans" , "Songwriter George's elder brother" , "George Gershwin's older brother, the lyricist" , "terrorists" .)