Beyond rule with riot spreading (8)
I believe the answer is:
ulterior
'beyond' is the definition.
(thesaurus)
'rule with riot spreading' is the wordplay.
'with' says to put letters next to each other.
'spreading' indicates anagramming the letters.
'rule' put after 'riot' is 'riotrule'.
'riotrule' is an anagram of 'ULTERIOR'.
(Other definitions for ulterior that I've seen before include "'Deliberately concealed, motive say (8)'" , "Beyond what is revealed or evident" , "hidden agenda" , "Secret extra (e.g. motive)" , "Intentionally concealed" .)