Of rabies (5)
I believe the answer is:
rabid
'of rabies' is the definition.
(I know this)
This is the entire clue.
(Other definitions for rabid that I've seen before include "Raging (having been bitten by a dog?)" , "Crazy" , "Extreme, fanatical" , "Mad; raging" , "Mad like deranged dog" .)