Official proving of a will (7)
I believe the answer is:
probate
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">official proving of a will</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for probate that I've seen before include "Formal proof of a will" , "Validation of will" , "Will-checking process" , "Legal proof of a will" , "document that proves a will is genuine" .)