Fever absent-minded vicar initially escapes (4)
I believe the answer is:
ague
'fever' is the definition.
(I've seen this before)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for ague that I've seen before include "Fit of shivering and shaking" , "met with cheek in Twelfth Night" , "Sweating, shivering, fit (once)" , "Chills and fever" , "Illness with fever and shivering, malaria say" .)