Those considered expendable fed on corn and nuts (6,6)
I believe the answer is:
cannon fodder
'those considered expendable' is the definition.
(cannon fodder can mean troops sent to die)
'fed on corn and nuts' is the wordplay.
'nuts' indicates anagramming the letters (nuts can mean crazy).
'fed'+'on'+'corn'+'and'='fedoncornand'
'fedoncornand' with letters rearranged gives 'CANNON-FODDER'.
(Other definitions for cannon fodder that I've seen before include "Soldiers considered expendable" , "Fanned condor (anag) - unfortunate soldiery?" , "Soldiers sent to die" , "Expendable men" , "circus performer to be fired?" .)