Not closed (4)
I believe the answer is:
open
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">not closed</span>' is the definition.<br/ ><span class="explanation-format__explanation">('open' is the opposite to 'closed')</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for open that I've seen before include "Contest that includes all comers" , "Not shut or secret" , "Affording access" , "Willing" , "golf contest" .)