Poet, reviewing article, includes terribly impolite letters (6)
I believe the answer is:
neruda
'poet' is the definition.
(poet Pablo Neruda)
'reviewing article includes terribly impolite letters' is the wordplay.
'reviewing' shows that the letters should be reversed in order (I've seen 'reviews' mean this (view the letters another way)).
'article' becomes 'an' (English indefinite article).
'includes' means one lot of letters goes inside another.
'terribly impolite letters' becomes 'dure' (I can't justify this - if you can you should believe this answer much more).
'an' placed around 'dure' is 'aduren'.
'aduren' in reverse letter order is 'NERUDA'.
Can you help me to learn more?
(Other definitions for neruda that I've seen before include "S American poet" , "Pablo --, Chilean poet and politician" .)