Never again (4)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">never again</span>' is the definition.<br/ ><span class="explanation-format__explanation">(once can mean one time only)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for once that I've seen before include "'... bitten, twice shy'" , "Cone (anag.)" , "In days past" , "At a previous time" , "in days of yore?" .)
(Other definitions for no more that I've seen before include "opposite of what Oliver wanted" , "Monroe (anag)" , "Nothing further" , "That's all - finished" , "Never again, that's the end of it" .)