Heads off (6)
I believe the answer is:
averts
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">heads off</span>' is the definition.<br/ ><span class="explanation-format__explanation">('avert' can be a synonym of 'head off')</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for averts that I've seen before include "Stops" , "Turns aside" , "Deflects, heads off" , "Of eyes or gaze, turns away" , "Wards off" .)