One-on-one Olympic event (4)
I believe the answer is:
epee
'one-on-one olympic event' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for epee that I've seen before include "Sharp-pointed duelling sword" , "Fencer's weapon" , "Fencing blade" , "Narrow fencing sword" , "Olympic event" .)