Serious-sounding fellow (6)

I believe the answer is:

ernest

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

I don't understand how the rest of the clue works.

(Other definitions for ernest that I've seen before include "- Bevin, twentieth century Labour politician" , "Resent (anag) - man" , "American writer . . . . . . Hemingway" , "fellow" , "A new genre is myth (anag) -- author" .)

I've seen this clue in The Mirror.

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