Starshine somehow loses its shine (9)
I believe the answer is:
'loses its shine' is the definition.
I can't judge whether this definition defines the answer.
'starshine somehow' is the wordplay.
'somehow' indicates an anagram.
'starshine' with letters rearranged gives 'TARNISHES'.
Can you help me to learn more?
(Other definitions for tarnishes that I've seen before include "discolorations?" , "stains" .)