Someone else (7)
I believe the answer is:
another
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">someone else</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 another that I've seen before include "second" , "Additional: alternative" , "A different one" , "Additional, one more" , "Player or person not yet named or selected" .)