Run out of fight, suffering with fever (4)
I believe the answer is:
ague
'fever' is the definition.
(illness causing fever)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for ague that I've seen before include "met with cheek in Twelfth Night" , "Illness with fever and shivering, malaria say" , "Feverish chill" , "attack" , "Complaint" .)