Works alone: career’s very unhappy, we hear (5,4)

I believe the answer is:

flies solo

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'works alone' is the definition.
I don't know anything about this answer so I cannot tell whether it can be defined by this definition.

'career's very unhappy we hear' is the wordplay.
'career's' becomes 'flies' (I am not sure about this - if you are sure you should believe this answer much more).
'very' becomes 'so' (both can mean 'extremely').
'unhappy' becomes 'low'.
'we hear' indicates a 'sounds like' (homophone) clue.
'low' is a homophone of 'lo'.
'flies'+'so'+'lo'='FLIES SOLO'

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I've seen this clue in The Times.

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