Filming device, for short (3)
I believe the answer is:
cam
'filming device 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 "Tributary of the Ouse" , "Rotating projection; river" , "Bump on a shaft for pushing another shaft" , "Shaft on a rotating part of machine" , "academic stream" .)