Finish and go too far? (5,3,4)

I believe the answer is:

cross the line

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'go too far?' is the definition.
(I've seen this in another clue)

I can't explain the rest of the clue.

(Other definitions for cross the line that I've seen before include "do it unacceptably badly" , "Overstep a boundary; sail over the equator" , "Complete the race" .)

I've seen this clue in The Times.

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