Fury from Blair endlessly (3)
I believe the answer is:
ire
'fury' is the definition.
(ire is intense rage)
'from blair endlessly' is the wordplay.
'from' indicates the answer is hidden within the clue.
'IRE' can be found hidden inside 'blair endlessly'.
(Other definitions for ire that I've seen before include "Strong feeling" , "Irritation, anger" , "Losing head" , "heat" , "resentment" .)