Scuppered the endless conflict before the gutless deserted (8)
I believe the answer is:
thwarted
'scuppered' is the definition.
(scupper can mean to thwart or stop)
'the endless conflict before the gutless deserted' is the wordplay.
'endless' means to remove the last letter.
'conflict before' becomes 'war' (war is a kind of conflict. I am not sure about the 'before' bit.).
'gutless' says to hollow out the word (remove centre letters).
'deserted' becomes 'd'.
'the' with its middle taken out is 'te'.
'the' with its final letter removed is 'th'.
'th'+'war'+'te'+'d'='THWARTED'
(Other definitions for thwarted that I've seen before include "Prevented from succeeding (in something)" , "Frustrated and foiled" , "stopped?" .)