Spanning (6)
I believe the answer is:
across
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">spanning</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 across that I've seen before include "what follows one here" , "Traversing" , "Horizontally" , "Clues like this" , "Towards the other side of" .)