A cortege is about class (10)
I believe the answer is:
categorise
'class' is the definition.
(I know that class is a more specific form of categorise)
'a cortege is about' is the wordplay.
'about' indicates an anagram.
'a'+'cortege'+'is'='acortegeis'
'acortegeis' is an anagram of 'CATEGORISE'.
(Other definitions for categorise that I've seen before include "class" , "Classify" , "Sort" .)