The smallest amount (4)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">the smallest amount</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 least that I've seen before include "Minimal amount" , "Of minimal significance" , "Smallest in amount or degree" , "Smallest in extent" , "Superlative form of 'little'" .)