Darts line (4)
I believe the answer is:
oche
'darts line' is the definition.
'oche' can be an answer for 'line' (I've seen this before). I also know that 'darts' relates to this answer.
This is all the clue.
(Other definitions for oche that I've seen before include "Heavy African knife" , "The mark at darts" , "Missile launchers stand behind this" , "Line from which a dart player throws" , "Line from which dart-players throw" .)