At darts, there's a line to toe (4)

I believe the answer is:

oche

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But I can't explain it at all! Could you help me understand?

(Other definitions for oche that I've seen before include "Heavy African knife" , "Line from which dart-players throw" , "Line from which a dart player throws" , "The mark at darts" , "Line from which dart-player throws" .)

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