Though upset about some lies, a poet is not rude (6)

I believe the answer is:

polite

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'is not rude' is the definition.
('polite' is the opposite to 'rude')

I cannot understand how the remainder of the clue works.

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(Other definitions for polite that I've seen before include "Well-behaved" , "Civil and good-mannered" , "Respectful and considerate" , "Having good manners, socially correct" , "Good mannered and civil" .)

I've seen this clue in the Evening Standard.

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