Throw away a fight (5)
I believe the answer is:
scrap
I believe this clue is a double definition.
'throw away' is the first definition.
(scrapping is a kind of throwing away)
'a fight' is the second definition.
(a scrap is a minor fight)
(Other definitions for scrap that I've seen before include "Abolish; leftover" , "Drop" , "Small (leftover) piece" , "Abandon" , "Fragment or morsel" .)