cue

An action or event that is a signal for somebody to do something.

The last words of a play actor's speech, serving as an intimation for the next actor to speak; any word or words which serve to remind an actor to speak or to do something; a catchword.

(electronics, computing) A marker or signal that triggers something, such as the start of an audio recording.

A hint or intimation.

(obsolete) Humour; temper of mind.