Void partner
I believe the answer is:
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">void partner</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for null that I've seen before include "Immaterial and void" , "Amounting to nothing" , "... and void, lacking any legal or binding force" , "Invalid, void" , "Without value or consequence" .)