Lesson in style (5)
I believe the answer is:
class
I believe this is a double definition.
'lesson' is the first definition.
(thesaurus)
'style' is the second definition.
(thesaurus)
'in' is the link.
(Other definitions for class that I've seen before include "Group - style" , "Category; lesson" , "sophistication" , "Genus" , "26 [ORDER]" .)