Justified (9)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">justified</span>' is the definition.<br/ ><span class="explanation-format__explanation">('warrant' can be a synonym of 'justify')</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Another definition for warranted that I've seen is " Justified or guaranteed".)
(Another definition for proved that I've seen is " Established beyond doubt".)