No danger signal (3,5)
I believe the answer is:
all clear
This could be a double definition.
'no danger' is the first definition.
Although both the answer and definition are singular nouns, I cannot understand how one could define the other.
'signal' is the second definition.
(all clear is a kind of signal)
Can you help me to learn more?
(Other definitions for all clear that I've seen before include "Understood" , "ARP signal" , "without any ambiguity" , "safety announcement" , "no longer misunderstood?" .)