On no occasion (5)
I believe the answer is:
never
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">on no occasion</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 never that I've seen before include "I refuse" , "At no time whatever" , "Under no circumstances" , "Do not give up!" , "Not in a month of Sundays" .)