Agreement to marry (10)
I believe the answer is:
engagement
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">agreement to marry</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 engagement that I've seen before include "Appointment - conflict" , "get this in the diary?" , "Fight" , "before wedding" , "Betrothal; appointment" .)