Begin to show surprise (5)

I believe the answer is:

start

This clue is a double definition.

'begin' is the first definition.
('start' can be a synonym of 'begin')

'show surprise' is the second definition.

'to' acts as a link.

(Other definitions for start that I've seen before include "Begin with sudden movement of surprise" , "Take the first step" , "Jerk" , "Jump suddenly" , "Commencement" .)

I've seen this clue in The Telegraph.

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