Act of defiance (4)
I believe the answer is:
dare
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">act of defiance</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 dare that I've seen before include "Be brave enough" , "Risk; challenge" , "Be courageous enough to try or do" , "Challenge to do something foolhardy" , "Take a chance - read about it" .)