Constant maiden shows style (5)
I believe the answer is:
class
'style' is the definition.
(thesaurus)
'constant maiden' is the wordplay.
'constant' becomes 'c' (mathematical abbreviation).
'maiden' becomes 'lass'.
'c'+'lass'='CLASS'
'shows' is the link.
(Other definitions for class that I've seen before include "It may appear after working" , "Lesson; social division" , "Study group" , "Group - style" , "Elegance - form" .)