Go on the stage in sudden terror (5)
I believe the answer is:
enter
'go on the stage' is the definition.
(I've seen this in another clue)
'in sudden terror' is the wordplay.
'in' says the answer is hidden in the clue.
'ENTER' is hidden in the letters of 'sudden terror'.
(Other definitions for enter that I've seen before include "Go in - set down" , "Join (for the first time)" , "Enroll, sign up" , "Gain admission" , "Move into" .)