Depleted (4,2)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">depleted</span>' is the definition.<br/ ><span class="explanation-format__explanation">('use up' can be a synonym of 'deplete')</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for used up that I've seen before include "Spent" , "Consumed, finished" , "Consumed completely" , "Exhausted the supply" .)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">depleted</span>' is the definition.<br/ ><span class="explanation-format__explanation">(sapping is a kind of depleting)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for sapped that I've seen before include "dug trench" , "Undermined or drained of strength" , "Gradually weakened" , "Gradually exhausted, drained of energy" , "Exhausted strength gradually" .)
(Other definitions for emptied that I've seen before include "Vacated" , "Drained" , "Discharged" , "Made vacant" , "Evacuated" .)