What is the origin of the idiom "in the clear" and when to use it?

The phrase "in the clear" has its origins in radio communications during the early 20th century. It was primarily used in military or aviation contexts, where clear and concise communication was crucial for operations. In radio transmissions, "clear" referred to a signal or message that was received without any interference or distortion. It is commonly employed in situations where there is a need to communicate that a person or situation is no longer at risk, facing obstacles, or experiencing uncertainty.