all clear

Từ điển Việt Anh Việt 4in1 - English Vietnamese 4 in 1 Dictionary

ˌall ˈclear BrE AmE , all-clear noun
the all clear
a) official permission to begin doing something
give (somebody)/get the all clear
We’ve got the all clear for the new project.
b) a signal such as a loud whistle that tells you that a dangerous situation has ended