The sun, for one (7)
'the sun for one' is the definition.
(sun is a kind of star)
This is the entire clue.
(Other definitions for star that I've seen before include "feature in film" , "White blaze on a horse's forehead" , "Outstanding entertainer" , "Brilliant person" , "Rush" .)
(Another definition for daystar that I've seen is " sun".)