Fantastic article about new musical instrument (8)
I believe the answer is:
clarinet
'musical instrument' is the definition.
(clarinet is a kind of musical instrument)
'fantastic article about new' is the wordplay.
'fantastic' is an anagram indicator.
'about' indicates putting letters inside.
'new' becomes 'n'.
'article' anagrammed gives 'clariet'.
'clariet' enclosing 'n' is 'CLARINET'.
(Other definitions for clarinet that I've seen before include "Blow that!" , "that works off wind" , "Music-maker" , "member of orchestra" , "Woodwind instrument - Artie Shaw played one" .)