Brief sharp pain (6)
I believe the answer is:
twinge
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">brief sharp pain</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 twinge that I've seen before include "Slight pang, maybe of conscience" , "Slight pain (of conscience?)" , "A small pang, of pain or concience" , "Sharp localised pain" , "Small, sharp pain" .)