Neolithic period (5,3)
I believe the answer is:
stone age
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">neolithic period</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 stone age that I've seen before include "Old time" , "Primitive period" , "Earliest known period of human culture" , "Go, senate to ancient era before metal was discovered" , "time long ago" .)