Try out, for purpose, what's fashionable (6)
I believe the answer is:
trendy
'fashionable' is the definition.
(similar in meaning)
'try out for purpose what's' is the wordplay.
'out' means to remove the last letter.
'for' is a charade indicator (letters next to each other).
'purpose' becomes 'end' (both can mean a goal).
'what's' becomes 'y' (I can't explain this - if you can you should believe this answer much more).
'try' with its last letter removed is 'tr'.
'tr'+'end'+'y'='TRENDY'
Can you help me to learn more?
(Other definitions for trendy that I've seen before include "Consciously fashionable" , "With it, a la mode" , "In fashion, of popular style" , "In vogue" , "With-it" .)