Star Wars weapon (5)
I believe the answer is:
laser
'star wars weapon' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for laser that I've seen before include "scientific device" , "Device that produces an intense beam of light" , "Light amplification by stimulated emission of radiation" , "Coherent light beam" , "Source of light; type of printer" .)