Neither/__ (3)
I believe the answer is:
nor
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">neither</span>' is the definition.<br/ ><span class="explanation-format__explanation">(eg in the phrase 'neither do I')</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for nor that I've seen before include "And not; Norman (abbr.)" , "Negative word" , "logic circuit" , "Neither pairing" , "Negative conjunction" .)