Rod accepts it as formally courteous (6)
I believe the answer is:
polite
'formally courteous' is the definition.
'polite' can be an answer for 'courteous' (similar in meaning). I'm not sure about the 'formally' bit.
'rod accepts it' is the wordplay.
'rod' becomes 'pole' (pole is a kind of rod).
'accepts' means one lot of letters goes inside another.
'pole' enclosing 'it' is 'POLITE'.
'as' acts as a link.
Can you help me to learn more?
(Other definitions for polite that I've seen before include "Well-mannered, courteous" , "Respectful and considerate" , "Well-spoken and civil" , "Mannerly, courteous" , "Civil and good-mannered" .)