Quarantine a saloon and it changes (9)

I believe the answer is:

isolation

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'quarantine' is the definition.
(I know that isolation is a type of quarantine)

I can't explain the remainder of the clue.

Can you help me to learn more?

(Other definitions for isolation that I've seen before include "loneliness" , "Separation, solitariness" , "Being separated" , "Staff in such a hospital working with" , "Remoteness" .)

I've seen this clue in The Daily Express.

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