Not perfectly upright (5)
I believe the answer is:
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">not perfectly upright</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>
(Other definitions for atilt that I've seen before include "Listing" , "Inclined" , "not quite horizontally" , "Hardly straight" , "Leaning over and nearly falling" .)