Fancy gentleman wearing flower (6)
I believe the answer is:
desire
'fancy' is the definition.
(thesaurus)
'gentleman wearing flower' is the wordplay.
'gentleman' becomes 'sir' (I've seen this before).
'wearing' indicates putting letters inside.
'flower' becomes 'dee' (River Dee).
'sir' put into 'dee' is 'DESIRE'.
(Other definitions for desire that I've seen before include "Long for (something)" , "Lust" , "Famous play: ''A Streetcar Named ......''" , "Concupiscence" , "Wish for strongly" .)