Least possible quantity (7)
I believe the answer is:
minimum
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">least possible quantity</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 minimum that I've seen before include "Bottom" , "Least recorded value" , "The least of smallest amount possible" , "Lowest point" , "Lowest value" .)