Free of restriction, don't be so jumpy (9)

I believe the answer is:

boundless

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'free' is the definition.
Both the answer and definition are adjectives. Perhaps you can see a link between them that I don't see?

I can't explain the remainder of the clue.

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(Other definitions for boundless that I've seen before include "Seemingly without limit" , "Having no limit, extensive" , "Without limits" , "Unlimited" .)

I've seen this clue in the Evening Standard.

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