Video recorder, for short (3)
I believe the answer is:
cam
'video recorder for short' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for cam that I've seen before include "academic stream" , "Projection on rotating shaft imparting motion" , "Bump on a shaft for pushing another shaft" , "River of eastern England" , "Rotating mechanism" .)