Bridge length (4)
I believe the answer is:
span
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">bridge length</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 span that I've seen before include "Team of two matched oxen" , "Extent - 9 inches" , "Distance or interval between two points" , "Arch across" , "Go across" .)