Basque separatist group (3)
I believe the answer is:
eta
'basque separatist group' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for eta that I've seen before include "when it might reach us?" , "Greek letter - time due (abbr)" , "Greek character?" , "European separatists, initially" , "Foreign letter" .)