Had corresponded, but was bound to conceal everything (7)

I believe the answer is:

tallied

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'had corresponded but' is the definition.
I can't tell whether this definition defines the answer.

'bound to conceal everything' is the wordplay.
'bound' becomes 'tied' ('tie' can be a synonym of 'bind').
'to conceal' indicates putting letters inside.
'everything' becomes 'all' (all things).
'tied' enclosing 'all' is 'TALLIED'.

'was' acts as a link.

Can you help me to learn more?

(Other definitions for tallied that I've seen before include "Agreed; calculated" , "Corresponded - kept score" , "Matched" , "Agreed, corresponded" , "Reckoned debt or score" .)

I've seen this clue in the Evening Standard.

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