Passionate about new and ostentatious clothing (6)
I believe the answer is:
finery
'ostentatious clothing' is the definition.
(I've seen this before)
'passionate about new' is the wordplay.
'passionate' becomes 'fiery' (similar in meaning).
'about' means one lot of letters goes inside another.
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'fiery' enclosing 'n' is 'FINERY'.
'and' is the link.
(Other definitions for finery that I've seen before include "Elaborate clothing, jewellery etc" , "Regalia" , "Elaborate clothes and accessories" , "Glad rags, best duds" , "Fancy clothes or trappings" .)