Battle without end to save revolutionary work in sport (5,4)
I believe the answer is:
water polo
'sport' is the definition.
(I know that water polo is a type of athletic game)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for water polo that I've seen before include "Sport for swimmers" , "event" , "Game played by tams of swimmers with large ball (5.4)" , "Swimming pool game" , "Seven-a-side game involving swimming" .)