Attempt to hide conclusion that's fashionable (6)
I believe the answer is:
trendy
'fashionable' is the definition.
(similar in meaning)
'attempt to hide conclusion' is the wordplay.
'attempt to' becomes 'try' (I've seen this in other clues).
'hide' means one lot of letters goes inside another.
'conclusion' becomes 'end' (something's conclusion is its end).
'try' going around 'end' is 'TRENDY'.
'that's' is the link.
(Other definitions for trendy that I've seen before include "Modish" , "Informally fashionable" , "In vogue" , "Smart" , "'Hip, fashionable (6)'" .)