First sign of tiredness, one agreed (7)

I believe the answer is:

tallied

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'one agreed' is the definition.
(I've seen this before)

I cannot understand how the rest of the clue works.

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

I've seen this clue in The Daily Express.

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