Raged about classification (5)
I believe the answer is:
grade
'classification' is the definition.
(grade is a kind of classification)
'raged about' is the wordplay.
'about' indicates anagramming the letters.
'raged' with letters rearranged gives 'GRADE'.
(Other definitions for grade that I've seen before include "Degree" , "Particular level of rank, quality, etc" , "School mark" , "Rank or status" , "one of the entertainment moguls" .)