Fashion's designation (5)
I believe the answer is:
style
I believe this clue is a double definition.
'fashion's' is the first definition.
('style' can be a synonym of 'fashion')
'designation' is the second definition.
(thesaurus)
(Other definitions for style that I've seen before include "approach?" , "Particular kind, of fashion say" , "Characteristic manner" , "Pointed pen" , "Refinement" .)