Instrument you fake for broadcast? I'm not sure (9)
I believe the answer is:
euphonium
'instrument' is the definition.
(I know that euphonium is a type of bass)
'fake for broadcast? i'm not sure' is the wordplay.
'fake for broadcast?' becomes 'euphon' (I can't explain this - if you can you should believe this answer much more).
'i'm' becomes 'i' (I've seen this in other clues).
'not sure' becomes 'um' (both might be said when unsure about something).
'euphon'+'i'+'um'='EUPHONIUM'
'you' is the link.
Can you help me to learn more?
(Other definitions for euphonium that I've seen before include "brass piece" , "Producer of notes" , "Brass band instrument" , "Tuba-like instrument" , "Wind instrument" .)