A guarantee (9)
I believe the answer is:
assurance
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">a guarantee</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for assurance that I've seen before include "what may follow life" , "Confidence (in abilities)" , "Certainty; life insurance" , "Confidence, certainty" , "Confidence, composure" .)