Dietary requirement (7)
I believe the answer is:
protein
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">dietary requirement</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 protein that I've seen before include "Combination of amino acids in living matter" , "A body chemical; pointer (anag.)" , "Not ripe (anag.)" , "Body-builder" , "Important dietary component" .)