Nothing sexy about Lynn perhaps being too keen (9)

I believe the answer is:

overacute

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'nothing sexy about lynn perhaps' is the definition.
I don't know anything about this answer so I can't judge whether this works.

'too keen' is the wordplay.
'too' becomes 'over' (I can't explain this - if you can you should believe this answer much more).
'keen' becomes 'acute' (synonyms).
'over'+'acute'='OVERACUTE'

'being' is the link.

Can you help me to learn more?

I've seen this clue in The Independent.

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