Consume entirely (3,2)
(Other definitions for eat up that I've seen before include "43 [TUCK] in" , "Finish course" , "Consume completely" , "Finish one's food" , "Exhaust" .)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">consume entirely</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for use up that I've seen before include "Expend" , "Entirely consume" , "Finish, exhaust" , "Consume (stocks)" , "Exhaust (resources)" .)