Extra rioting on earth (7)
I believe the answer is:
another
'extra' is the definition.
(thesaurus)
'rioting on earth' is the wordplay.
'rioting' is an anagram indicator (I've seen this in other clues).
'on'+'earth'='onearth'
'onearth' is an anagram of 'ANOTHER'.
(Other definitions for another that I've seen before include "second" , "A different one" , "encore?" , "Player or person not yet named or selected" , "Additional, one more" .)