Huge riots turned out to be justified (9)
I believe the answer is:
righteous
'be justified' is the definition.
(thesaurus)
'huge riots turned out' is the wordplay.
'turned out' indicates anagramming the letters.
'huge'+'riots'='hugeriots'
'hugeriots' with letters rearranged gives 'RIGHTEOUS'.
'to' is the link.
(Other definitions for righteous that I've seen before include "Just, upright" , "Morally justified" , "Virtuous, free from sin or guilt" , "Moral - virtuous" , "law-abiding" .)