Broker, representative (5)
I believe the answer is:
agent
<span class="explanation-format__ClueExplanation">This clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">broker</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >'<span class="explanation-format__original">representative</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(agent is a kind of representative)</span><br/ ><br/ ></span>
(Other definitions for agent that I've seen before include "envoy" , "Substance that exerts some force or effect" , "Double-zero-seven, for example" , "Traveller" , "Bond, e.g." .)