Substantiate (7)
I believe the answer is:
confirm
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">substantiate</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I know that substantiate can be written as confirm)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for confirm that I've seen before include "Bishop may" , "Authenticate" , "Establish the truth of" , "Ratify; establish" , "Strengthen" .)