Absent; lost (7)
I believe the answer is:
missing
<span class="explanation-format__ClueExplanation">I believe this clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">absent</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I know that absent can be written as missing)</span><br/ ><br/ >'<span class="explanation-format__original">lost</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(similar in meaning)</span><br/ ><br/ ></span>
(Other definitions for missing that I've seen before include "Absent with location unknown" , "Lost without" , "Not to be found" .)