It produces an intense beam of light (5)
I believe the answer is:
laser
'it produces an intense beam of light' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for laser that I've seen before include "Powerful light source" , "E.g. surgical light-beam" , "Source of light; type of printer" , "type of surgery" , "scientific instrument" .)