Ray gun sound (3)
I believe the answer is:
zap
'ray gun sound' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for zap that I've seen before include "Keep changing TV channels" , "Destroy, obliterate" , "Kill or shoot (in a microwave oven?)" , "Hit (colloq.)" , "Attack" .)