Sudden outburst (5-2)
I believe the answer is:
flare-up
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">sudden outburst</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 flare-up that I've seen before include "Burst into flames" , "Sudden outbreak (of violence, etc)" , "Suddenly get angry" , "Explosion of emotion" , "Suddenly burn brightly" .)