Intense beam of light (5)
I believe the answer is:
laser
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">intense beam of light</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for laser that I've seen before include "Device producing an intense light beam - kind of sailing dinghy" , "E.g. surgical light-beam" , "Device producing thin beam of light" , "Scientific apparatus" , "Optical device producing an intense beam of light" .)