Composer plays roles in singles (9)

I believe the answer is:

bachelors

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'singles' is the definition.
Although both the answer and definition are verbs in their -s form, I cannot understand how they can define each other.

'composer plays roles in' is the wordplay.
'composer' becomes 'bach' (Johann Sebastian Bach).
'plays' indicates an anagram.
'in' indicates putting letters inside.
'roles' anagrammed gives 'elors'.
'bach' placed inside 'elors' is 'BACHELORS'.

Can you help me to learn more?

(Another definition for bachelors that I've seen is " Available men".)

I've seen this clue in The Mirror.

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