Announcement from a cockpit, for short (3)
I believe the answer is:
eta
'announcement from a cockpit for short' 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 "Militant Basque organisation - Greek letter" , "Letter of Greek alphabet" , "When you'd expect to see" , "Greek letter E; estimated time of arrival (abbr.)" , "When one is due" .)