Matter or topic (7)
I believe the answer is:
subject
<span class="explanation-format__ClueExplanation">This clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">matter</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >'<span class="explanation-format__original">topic</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ ></span>
(Other definitions for subject that I've seen before include "person photographed" , "issue" , "guinea pig" , "In school possibly English" , "What ruler is not" .)