Prompt (an actor) (3)
I believe the answer is:
cue
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">prompt an actor</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for cue that I've seen before include "Billiards stick" , "Actor's words" , "Actor's prompt" , "Snooker rod" , "Prompt; signal" .)