Return to the stage and do double-take? (5)
I believe the answer is:
react
'do double-take?' is the definition.
(to double-take is to react in surprise)
I don't understand how the rest of the clue works.
(Other definitions for react that I've seen before include "Show opposition" , "Behave in response" , "Respond to something" , "Acknowledge" , "provide an answer" .)