In style, trendy (6)
I believe the answer is:
modish
I believe this is a double definition.
'in style' is the first definition.
(synonyms)
'trendy' is the second definition.
(I've seen this in another clue)
(Other definitions for modish that I've seen before include "In vogue or fashion" , "In fashion or style" , "Temporarily fashionable" , "I'm shod in the current fashion" , "Fashionable, in style" .)