When not working, given to being casual (3-6)

I believe the answer is:

off-handed

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'being casual' is the definition.
Both the answer and definition are adjectives.
Perhaps there's a link between them I don't understand?

'when not working given' is the wordplay.
'when' becomes 'handed' (I can't explain this - if you can you should believe this answer much more).
'not working' becomes 'off' (switched off).
'given' says to put letters next to each other.
'handed' put after 'off' is 'OFF-HANDED'.

'to' is the link.

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I've seen this clue in the Evening Standard.

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