Not shut tight (4)
I believe the answer is:
ajar
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">not shut tight</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for ajar that I've seen before include "Not to answer" , "Half-open" , "Not quite closed" , "Left open" , "Not quite shut" .)