One never says anything original (6)
I believe the answer is:
parrot
'one' is the definition.
Although both the answer and definition are singular nouns, I don't understand how they can define each other.
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for parrot that I've seen before include "Copycat who does not understand words or acts imitated" , "Repeater" , "Chant" , "Mimic speech like colourful bird" , "Squawking bird" .)