they're put up in a fight (5)
I believe the answer is:
dukes
'they're put up in a fight' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for dukes that I've seen before include "Noblemen" , "Titled gents or slangy fists" , "eg 21, 22 and Plaza-Toro" , "Peers of the realm" .)