Greets the silly ass carrying the instrument (7)
I believe the answer is:
salutes
'greets' is the definition.
(saluting is a kind of greeting)
'silly ass carrying the instrument' is the wordplay.
'silly' indicates anagramming the letters.
'carrying' is an insertion indicator.
'the instrument' becomes 'lute' (lute is a kind of instrument).
'ass' anagrammed gives 'sas'.
'sas' placed around 'lute' is 'SALUTES'.
'the' acts as a link.
(Other definitions for salutes that I've seen before include "Greets" , "Military greetings" , "Brief inspection" .)