Malarial fever (4)
I believe the answer is:
ague
'malarial fever' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for ague that I've seen before include "Sweating, shivering, fit (once)" , "Malarial fever; chill" , "Malaria, for example" , "Fit of shivering and shaking" , "Feverish illness" .)