Fashionably nostalgic (5)
I believe the answer is:
retro
'fashionably nostalgic' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for retro that I've seen before include "Predatory fish" , "consciously old-fashioned" , "Type of rocket; backward-looking" , "Fashion reminiscent of the past" , "Style derived from the past" .)