More remarkable result produced by outsider (8)

I believe the answer is:

stranger

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'outsider' is the definition.
(I've seen this before)

I cannot understand how the remainder of the clue works.

(Other definitions for stranger that I've seen before include "Truth can be ... than fiction" , "One who is little known" , "visitor" , "Non-acquaintance" , "Person one doesn't know" .)

I've seen this clue in The Globe and Mail.

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