Opening, hole (8)
I believe the answer is:
aperture
I believe this is a double definition.
'opening' is the first definition.
(aperture is a kind of opening)
'hole' is the second definition.
(aperture is a kind of hole)
(Other definitions for aperture that I've seen before include "Device controlling amount of light admitted" , "An opening that admits light" , "Narrow opening" , "Opening through which light enters a camera" , "Opening, to let light enter a camera perhaps" .)