Prevent from happening (6)
(Other definitions for kibosh that I've seen before include "Finish off" , "Put this on something and stop it from happening" , "Fatal to put this on" , "Terminate" , "Make impossible to happen" .)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">prevent from happening</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 avert that I've seen before include "Head off" , "Fend off" , "Prevent from occurring" , "Deflect away" , "Turn aside, perhaps gaze" .)
(Other definitions for forestall that I've seen before include "Arrive first" , "Take action before" , "Anticipate" , "Obstruct by taking advance action" , "Check" .)