Judge, umpire (7)
I believe the answer is:
arbiter
<span class="explanation-format__ClueExplanation">I believe this is a double definition.<br/ ><br/ >'<span class="explanation-format__original">judge</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I know that arbiter is a type of judge)</span><br/ ><br/ >'<span class="explanation-format__original">umpire</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I know that umpire can be written as arbiter)</span><br/ ><br/ ></span>
(Other definitions for arbiter that I've seen before include "One judges a disputed issue" , "One decides in disputes" , "Source of authority" , "One must exercise judgment" , "Ref" .)