Feverish chill (4)
I believe the answer is:
ague
'feverish chill' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for ague that I've seen before include "Illness with fever and shivering, malaria say" , "Chills and fever" , "Fit of the shakes" , "Feverish chill" , "Fit of shivering and shaking" .)