Strive, struggle (5)
I believe the answer is:
fight
I believe this clue is a double definition.
'strive' is the first definition.
(thesaurus)
'struggle' is the second definition.
(I know that struggle can be written as fight)
(Other definitions for fight that I've seen before include "Conflict" , "(Take part in) battle" , "Strive - struggle" , "Scrap" , "Contest" .)