Giant star in Scorpius (7)
I believe the answer is:
antares
'giant star in scorpius' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for antares that I've seen before include "Red supergiant star in Scorpio; nae star (anag.)" , "brilliant point" , "Star reddened" , "Red supergiant star in Scorpius" , "RS [RED STAR]" .)