Jonathan was not slow (5)

I believe the answer is:

swift

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'jonathan' is the definition.
(I know that jonathan can be written as Swift)

I don't understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for swift that I've seen before include "Jonathan ..., clergyman and satirist" , "Anglo-Irish satirist" , "like a cheetah?" , "A bird; Gulliver author" , "Rapid - writer - bird" .)

I've seen this clue in the Evening Standard.

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