Critical warning
'critical warning' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for red alert that I've seen before include "State of readiness for imminent threat" , "Severe 1 dn" , "Warning signal" , "State of readiness for imminent crisis" , "Alarm" .)
'critical warning' is the definition.
(I've seen this in another clue)
This is the entire clue.