NATO alphabet ender (4)
I believe the answer is:
zulu
'nato alphabet ender' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for zulu that I've seen before include "Communications code for Z" , "Bantu warrior" , "Member of a South African tribe" , "Final letter heard on radio" , "Member of a people of southeast Africa" .)