Historical eras (4)
I believe the answer is:
ages
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">historical eras</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for ages that I've seen before include "Matures" , "A long time (colloq.)" , "Grows old like sage" , "Gets older" , "Awfully long time" .)