One too careless for regular employment? (6,6)

I believe the answer is:

casual worker

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'one too' is the definition.
I know nothing about this answer so I cannot tell whether it can be defined by this definition.

'careless for regular employment?' is the wordplay.
'careless' becomes 'casual' (similar in meaning).
'for' says to put letters next to each other.
'regular employment?' becomes 'worker' (I can't justify this - if you can you should believe this answer much more).
'casual'+'worker'='CASUAL WORKER'

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I've seen this clue in The Globe and Mail.

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