Significantly overweight (5)
I believe the answer is:
obese
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">significantly overweight</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for obese that I've seen before include "Extremely fat" , "Morbidly overweight" , "carrying remarkable weight" , "Extremely portly" , "Clinically overweight" .)