Instrument you fake the sound of with hesitation (9)
I believe the answer is:
euphonium
'instrument' is the definition.
(I know that euphonium is a type of bass)
'you fake the sound of with hesitation' is the wordplay.
I cannot really understand how this works, but
'you' could be 'u' (homophones) and 'u' is found in the answer.
'of' could be 'o' and 'o' is present in the answer.
'hesitation' could be 'um' (sound made when hesitating) and 'um' is present in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for euphonium that I've seen before include "Brass band instrument" , "Bass-tenor tuba" , "Band member" , "Wind instrument" , "brass piece" .)