1. Adjective. Transparent or having no color. In lighting: clear, CL, no color, NC, N/C, white, and open white all mean the same thing.
2. Verb. To remove or evacuate. "Clear the programmer." "Clear the props." "Clear the decks, light the lights."
3. Signal that a task has been completed, or OK to proceed. "All clear." A stagehand calls a clear when an actor is out of the path of a moving platform, so the Stage Manager can call the cue for the platform to move.