circa (5)
I believe the answer is:
about
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">circa</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 about that I've seen before include "On the topic of" , "Regarding" , "In conection with, all around" , "in action" , "Concerning or around" .)