Knightly behaviour (8)
I believe the answer is:
chivalry
'knightly behaviour' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for chivalry that I've seen before include "Knightly behaviour" , "Courtesy and consideration towards women, as from knights of old" , "Gallantry" , "Courtesy and kind behaviour towards weaker people" , "Almost defunct code of courtesy towards women" .)