Starshine somehow loses its shine (9)

I believe the answer is:

tarnishes

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'loses its shine' is the definition.
I can't tell whether this definition defines the answer.

'starshine somehow' is the wordplay.
'somehow' indicates anagramming the letters.
'starshine' is an anagram of 'TARNISHES'.

Can you help me to learn more?

(Other definitions for tarnishes that I've seen before include "discolorations?" , "stains" .)

I've seen this clue in the Sydney Morning Herald.

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