An outstanding singer perhaps (8)

I believe the answer is:

caroller

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'an outstanding singer' is the definition.
'caroller' can be an answer for 'singer' (caroller is a kind of singer). I am unsure of the 'an outstanding' bit.

I cannot understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for caroller that I've seen before include "Singer" , "that makes Christmas music" .)

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

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