Authentic report of sizeable Scottish settlement (8)

I believe the answer is:

sterling

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'authentic' is the definition.
(thesaurus)

I don't understand the rest of the clue.

(Other definitions for sterling that I've seen before include "Excellent, first-class" , "Of solid worth, like British money" , "Genuine - money" , "banking standard" , "first-class quality" .)

I've seen this clue in The Independent.

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