Accidental success (5)
I believe the answer is:
fluke
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">accidental success</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 fluke that I've seen before include "land, by chance" , "Lucky chance" , "Fortuitously secure" , "One lucky" , "Lucky break" .)