An expression of surprise in a legal document (6)

I believe the answer is:

indeed

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'an expression of surprise' is the definition.
I can't tell whether this defines the answer.

'in a legal document' is the wordplay.
'a legal document' becomes 'deed ' (deed is a kind of legal document).
'in'+'deed'='INDEED'

Can you help me to learn more?

(Other definitions for indeed that I've seen before include "Surely" , "Without question" , "Actually -- denied (anag)" , "Expression of interest, incredulity or contempt" , "Certainty" .)

I've seen this clue in The Globe and Mail.

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