Fashionable sound? (5)
I believe the answer is:
swish
I believe this clue is a double definition.
'fashionable' is the first definition.
(I've seen this before)
'sound?' is the second definition.
(swish is a kind of sound)
(Other definitions for swish that I've seen before include "Stylish (sl.)" , "Impressively fashionable" , "Impressively smart" , "Extravagant" , "Smart; stylish" .)