If someone in authority gives you the all clear, they give you permission to continue with a plan or activity, usually after a problem has been sorted out. I was given the all clear by the doctor to resume playing. = go-ahead. A signal, usually by siren, that an air raid is over or a danger has passed. a) official permission to begin doing something give (sb)/get the all clear
The all clear is a signal that a dangerous situation, for example an air raid, has ended. The all clear was sounded about 10 minutes after the alert was given. All clear is also a convention. `All clear,' Misha growled