Organise race series (3)
I believe the answer is:
run
I believe this is a triple definition!
'organise' is the first definition.
(I've seen this before)
'race' is the second definition.
(running is a kind of racing)
'series' is the third definition.
(run is a kind of series)
(Other definitions for run that I've seen before include "Flow; function" , "goal for England player?" , "travel with > expedition" , "Unit of score in cricket" , "Discharge" .)