When (4)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">when</span>' is the definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for once that I've seen before include "Sometime" , "In former times" , "not repeatedly" , "Some time back" , "At some time past" .)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">when</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>