Mound stat (3)
I believe the answer is:
era
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">mound stat</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for era that I've seen before include "quite some time" , "Geological age" , "Series of years" , "day" , "Important time" .)