Earnestly, genuinely (9)
I believe the answer is:
sincerely
<span class="explanation-format__ClueExplanation">This clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">earnestly</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(thesaurus)</span><br/ ><br/ >'<span class="explanation-format__original">genuinely</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ ></span>
(Other definitions for sincerely that I've seen before include "without hypocrisy" , "With genuine feeling" , "With genuine feelings" , "Genuinely, honestly" , "Last word in letter" .)