Heel over; slant (4)
I believe the answer is:
tilt
<span class="explanation-format__ClueExplanation">This clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">heel over</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >'<span class="explanation-format__original">slant</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I know that slant can be written as tilt)</span><br/ ><br/ ></span>
(Other definitions for tilt that I've seen before include "Slant - joust" , "Cause to slope or incline" , "Heel over" , "Joust; bias" , "Slight inclination" .)