Debut? That’s a shock! (5)

I believe the answer is:

start

I believe this clue is a double definition.

'debut?' is the first definition.
(debut is a kind of start)

'that's a shock' is the second definition.
(to give someone a start is to shock them)

(Other definitions for start that I've seen before include "Initiate" , "Take the first step" , "launch" , "Beginning" , "Opening - jump" .)

I've seen this clue in The Times.

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