Decline to become enamoured of (4)

I believe the answer is:

fall

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'decline' is the definition.
(synonyms)

I don't understand the remainder of the clue.

(Other definitions for fall that I've seen before include "The American autumn" , "Autumn; plummet" , "Rapid descent" , "Autumn in America" , "What tripper risks" .)

I've seen this clue in the Evening Standard.

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