Indeed, really (5)
I believe the answer is:
truly
<span class="explanation-format__ClueExplanation">I believe this is a double definition.<br/ ><br/ >'<span class="explanation-format__original">indeed</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >'<span class="explanation-format__original">really</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ ></span>
(Other definitions for truly that I've seen before include "Verily" , "Honestly" , "Genuinely, properly" , "Really, genuinely" , "Indeed" .)