More youthful (7)
I believe the answer is:
younger
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">more youthful</span>' is the definition.<br/ ><span class="explanation-format__explanation">('young' can be similar in meaning to 'youthful')</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for younger that I've seen before include "Less mature" , "Less aged" , "More juvenile" , "More youthful" , "more boyish" .)