Not us (4)

I believe the answer is:
them
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">not us</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for them that I've seen before include "Perhaps, the Opposition" , "(To/from) those people" , "Others" , "... in another case, they" , "people objectively" .)