Dash or marathon (4)
I believe the answer is:
race
I believe this is a double definition.
'dash' is the first definition.
(I know this)
'marathon' is the second definition.
(I've seen this in another clue)
(Other definitions for race that I've seen before include "People - sprint - competition" , "Run - competition" , "Rapid current" , "put their skates on" , "Contest; nation" .)