Run-down but sounding warm and bright (7)

I believe the answer is:

summary

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'bright' is the definition.
Both the answer and definition are adjectives. Maybe you can see an association between them that I can't see?

I cannot understand how the rest of the clue works.

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(Other definitions for summary that I've seen before include "Abstract, short version" , "Precis, gist" , "Recapitulation" , "Brief" , "Resume" .)

I've seen this clue in The Guardian.

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