It’s of marginal significance (4)

I believe the answer is:

edge

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'significance' is the definition.
The definition and answer can be both human attributes as well as being singular nouns.
Maybe you can see an association between them that I don't see?

I don't understand the remainder of the clue.

Can you help me to learn more?

(Other definitions for edge that I've seen before include "Move slowly" , "Surface boundary" , "Brim" , "The part farthest from the middle" , "Final line" .)

I've seen this clue in the Evening Standard.

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