Eons (4)
I believe the answer is:
ages
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">eons</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 ages that I've seen before include "A long time (colloq.)" , "Historic periods or prolonged time" , "Rock of - - (hymn)" , "Grows old like sage" , "(What seems) a very long time" .)