Aficionado hosting fashionable banker (9)
I believe the answer is:
financier
'banker' is the definition.
(I've seen this before)
'aficionado hosting fashionable' is the wordplay.
'aficionado' becomes 'fancier' (I've seen this in another clue).
'hosting' means one lot of letters goes inside another.
'fashionable' becomes 'in' (in can mean fashionable or trendy).
'fancier' enclosing 'in' is 'FINANCIER'.
(Other definitions for financier that I've seen before include "One dealing in big money" , "Merchant banker, perhaps" , "City man" , "Gnome" , "Investor" .)