Ten-year span (6)
I believe the answer is:
decade
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">ten-year span</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 decade that I've seen before include "The 1960s, for example" , "Tenth of a century" , "The noughties maybe" , "Ten year period" , "Period of ten years" .)