Communicate; negotiate (6)
I believe the answer is:
liaise
<span class="explanation-format__ClueExplanation">I believe this clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">communicate</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >'<span class="explanation-format__original">negotiate</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I know that liaise is a more specific form of the action negotiate)</span><br/ ><br/ ></span>
(Other definitions for liaise that I've seen before include "Mediate" , "Act as a link between groups" , "Mutually cooperate" , "Cooperate on a matter of mutual concern" , "Collaborate" .)