Levin or Gershwin (3)
I believe the answer is:
ira
This clue is a double definition.
'levin' is the first definition.
(I've seen this in another clue)
'gershwin' is the second definition.
(lyricist Ira Gershwin, brother of George)
(Other definitions for ira that I've seen before include "terrorists" , "Songwriter George's elder brother" , "Illegal organisation, in short" , "nationalists" , "Brother of George Gershwin" .)