Sheer chaos with variable dissent (6)
I believe the answer is:
heresy
'dissent' is the definition.
(thesaurus)
'sheer chaos with variable' is the wordplay.
'chaos with' indicates an anagram.
'variable' becomes 'y' (I've seen this in other clues).
'sheer' mixed up with 'y' can make 'HERESY'.
(Other definitions for heresy that I've seen before include "Belief that's anathema to the orthodox" , "this view is unacceptable" , "you shouldn't believe it" , "Belief that rejects the orthodox tenets of a religion" , "unorthodox views" .)