Elegance of a lesson (5)
I believe the answer is:
class
I believe this clue is a double definition.
'elegance' is the first definition.
(class is a kind of elegance)
'a lesson' is the second definition.
(thesaurus)
'of' acts as a link.
(Other definitions for class that I've seen before include "pupils?" , "School group" , "Genus" , "Fine" , "Type; social level" .)