Years of youth (5)
I believe the answer is:
teens
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">years of youth</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 teens that I've seen before include "13-19 age group" , "The years 13 to 19" , "Years 13-19" , "seven-year period" , "Between 12 and 20" .)