What a former president would cry out in surprise? (6)

I believe the answer is:

crikey

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'what a former president would' is the definition.
I can't judge whether this definition defines the answer.

'cry out in surprise?' is the wordplay.
'out' means to remove the last letter.
'in surprise?' becomes 'ikey' (I can't explain this - if you can you should believe this answer much more).
'cry' with its last letter removed is 'cr'.
'cr'+'ikey'='CRIKEY'

Can you help me to learn more?

(Other definitions for crikey that I've seen before include "Gosh!" , "Good heavens!" , "Good Lord!" , "by George" , "Cor blimey!" .)

I've seen this clue in the Evening Standard.

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