Self-inflicted loss (3,4)
I believe the answer is:
own goal
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">self-inflicted loss</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for own goal that I've seen before include "Football score at the wrong end" , "Football mishap" , "Act harming one's personal interests" , "Costly footballing error" , "Act harming the perpetrator's interests" .)