Good manners (8)
(Other definitions for courtesy that I've seen before include "Polite behaviour" , "Civility, politeness" , "Respectful and considerate behaviour" , "Good manners" , "good breeding" .)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">good manners</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for breeding that I've seen before include "Cultivating" , "Reproduction - refinement" , "strain" , "Upbringing" , "Good manners" .)