Through which to view star? (8)
I believe the answer is:
skylight
This clue could be a double definition.
'through which to view' is the first definition.
(skylight is a type of window)
'star?' is the second definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
(Other definitions for skylight that I've seen before include "Window in a roof or ceiling" , "Attic window" .)