Delirium (5)
'delirium' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for fever that I've seen before include "State of high excitement" , "Yellow, for example" , "Flu symptom: frenzy" , "Heat of disease or extreme excitement" , "eg Malaria" .)
'delirium' is the definition.
(I know that delirium can be written as frenzy)
This is the entire clue.
(Other definitions for frenzy that I've seen before include "Delirium - fury" , "Period of wild behaviour" , "State of violent mental agitation" , "Wild bout of activity" , "Delirious excitement" .)