Fight, struggle (6)
I believe the answer is:
battle
This clue is a double definition.
'fight' is the first definition.
(I know that fight can be written as battle)
'struggle' is the second definition.
(a struggle or ordeal might be called a battle)
(Other definitions for battle that I've seen before include "Lengthy fight" , "Fight between armies" , "A fight between large forces" , "Sustained conflict" , "Military engagement" .)