Excellent beginning, but not ending (4)
I believe the answer is:
star
'excellent' is the definition.
(star can mean excellent or top-quality)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for star that I've seen before include "Outstanding entertainer" , "A .... called Henry (Roddy Doyle)" , "Twinkling celestial body" , "Five- or six-pointed figure" , "A heavenly body or film favourite" .)