Gentlemanliness (8)
I believe the answer is:
chivalry
'gentlemanliness' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for chivalry that I've seen before include "Medieval knightly system of honour" , "Knightly code of honour" , "Courtesy and kind behaviour towards weaker people" , "Courtesy and consideration towards women, as from knights of old" , "Code of behaviour followed by medieval knights" .)