Bear witness to (6)
I believe the answer is:
attest
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">bear witness to</span>' is the definition.<br/ ><span class="explanation-format__explanation">(attesting is a kind of bearing witness to)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for attest that I've seen before include "Vouch for" , "Corroborate" , "Affirm by oath" , "University town" , "Give evidence - sounds a trial" .)