Flower borders? (5)

I believe the answer is:

banks

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'flower borders?' is the definition.
The answer and definition can be both man-made objects as well as being plural nouns.
Perhaps you can see an association between them that I don't see?

This is the entire clue.

Can you help me to learn more?

(Other definitions for banks that I've seen before include "Relies" , "Financial institutions" .)

I've seen this clue in The Telegraph.

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