A code some get wrong outright! (5)

I believe the answer is:

morse

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'a code' is the definition.
(Morse code)

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

(Other definitions for morse that I've seen before include "TV inspector" , "Radio code inventor" , "used to transmit messages" , "Colin Dexter's fictional detective" , "Samuel ---, telegraph inventor" .)

I've seen this clue in the Evening Standard.

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