Surprise by getting the old right in! (7)

I believe the answer is:

startle

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'surprise by' is the definition.
'startle' can be an answer for 'surprise' (thesaurus). I'm unsure of the 'by' bit.

'the old right in' is the wordplay.
'the old' becomes 'stale' (I've seen this before**).
'right' becomes 'rt'.
'in' is an insertion indicator.
'stale' enclosing 'rt' is 'STARTLE'.

'getting' acts as a link.

Can you help me to learn more?

(Other definitions for startle that I've seen before include "Astonish" , "Rattles (anag.)" , "Surprise with starlet" , "Cause shock to" , "Make jump" .)

I've seen this clue in the Evening Standard.

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