Appertain (6)
I believe the answer is:
belong
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">appertain</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for belong that I've seen before include "feel like one of the family" , "'Be part of, fit in (6)'" , "find a place?" , "Be correctly assigned" , "Appertain" .)