Not so old (7)
I believe the answer is:
younger
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">not so old</span>' is the definition.<br/ ><span class="explanation-format__explanation">(less old)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for younger that I've seen before include "More juvenile" , "Not so old" , "Less grey" , "More youthful" , "Comparatively raw" .)