In a Sinatra song, the same Scots stars (5,3)
I believe the answer is:
milky way
'stars' is the definition.
'in a sinatra song the same scots' is the wordplay.
'in' is an insertion indicator.
'a sinatra song' becomes 'myway' (My Way is a Frank Sinatra song).
'the same scots' becomes 'ilk' (Scots term for 'the same').
'myway' enclosing 'ilk' is 'MILKY WAY'.
(Other definitions for milky way that I've seen before include "Starry band of light across the night sky" , "Lots of stars" , "Galaxy containing our solar system" , "Star-studded band" , "Millions of stars in a band of light across the night sky" .)