Proves (7)
I believe the answer is:
attests
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">proves</span>' is the definition.<br/ ><span class="explanation-format__explanation">(attesting is a kind of proving)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for attests that I've seen before include "Certifies" , "Authenticates or affirms to be true" , "Gives evidence in court" , "Bears witness" , "Sat test (anag.)" .)