Scheduled time for military operation? 00:00 (4,4)
I believe the answer is:
zero hour
'scheduled time' is the definition.
'zero hour' can be an answer for 'time' (zero hour is a kind of time). I am not certain of the 'scheduled' bit.
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for zero hour that I've seen before include "Start time" , "Time to initiate a military operation" , "Exact time for launch of military action" , "when one's carried out" , "when operation is due to start" .)