Side isn't changing order (8)
I believe the answer is:
tidiness
'order' is the definition.
(tidiness is a kind of order)
'side isn't changing' is the wordplay.
'changing' indicates an anagram.
'side'+'isnt'='sideisnt'
'sideisnt' anagrammed gives 'TIDINESS'.
(Other definitions for tidiness that I've seen before include "Quality of neatness and orderliness" , "Orderly quality" , "sense of order" , "good order" , "Insisted on neatness." .)