Rod keeps sex-appeal cultivated (6)
I believe the answer is:
polite
'cultivated' is the definition.
('polite' can be a synonym of 'cultivated')
'rod keeps sex-appeal' is the wordplay.
'rod' becomes 'pole' ('pole' can be a synonym of 'rod').
'keeps' means one lot of letters goes inside another.
'sex appeal' becomes 'it'.
'pole' going around 'it' is 'POLITE'.
(Other definitions for polite that I've seen before include "Well-behaved" , "Respectful and considerate" , "Having good manners, socially correct" , "Cultivated" , "Of courteous manners" .)