Intense, raging fire in which five died (6)
I believe the answer is:
fervid
'intense' is the definition.
(thesaurus)
'raging fire in which five died' is the wordplay.
'raging' indicates an anagram.
'in which' is an insertion indicator.
'five' becomes 'v' ('V' can be a synonym of 'five').
'died' becomes 'd'.
'fire' anagrammed gives 'feri'.
'feri' placed around 'v' is 'fervi'.
'fervi'+'d'='FERVID'
(Other definitions for fervid that I've seen before include "Ardent, impassioned" , "Fiery and passionate" , "Heated - vehement" , "Zealous" , "Intensely enthusiastic" .)