Childhood plumpness (5,3)
I believe the answer is:
puppy fat
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">childhood plumpness</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 puppy fat that I've seen before include "Childhood tubbiness, often lost by maturity" , "Early chubbiness" , "Youthful plumpness" , "Childhood plumpness" , "young blubber" .)