At liberty to turn and coast (4-5)

I believe the answer is:

free-wheel

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

'at liberty to turn' is the wordplay.
'at liberty' becomes 'free' (similar in meaning).
'to turn' becomes 'wheel' (I've seen this before).
'free'+'wheel'='FREE-WHEEL'

'and' is the link.

Can you help me to learn more?

I've seen this clue in the Sydney Morning Herald.

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