Italian carrying back sound content to inflict an invasion (6)
I believe the answer is:
irrupt
'inflict an invasion' is the definition.
'italian carrying back sound content' is the wordplay.
'italian' becomes 'it'.
'carrying' indicates putting letters inside.
'back' says the letters should be written in reverse.
'sound content' becomes 'purr' (I've seen this before).
'purr' back-to-front is 'rrup'.
'it' going around 'rrup' is 'IRRUPT'.
'to' acts as a link.
(Other definitions for irrupt that I've seen before include "Break, rush, in" , "Enter forcibly or violently" , "Enter forcibly and suddenly" .)