Breaking instrument? It's flipping working! (9)
I believe the answer is:
violation
'breaking' is the definition.
(thesaurus)
'instrument? it's flipping working' is the wordplay.
'instrument?' becomes 'viola' (viola is a kind of instrument**).
'flipping' is a reversal indicator.
'working' becomes 'on'.
'it' in reverse letter order is 'ti'.
'viola'+'ti'+'on'='VIOLATION'
(Other definitions for violation that I've seen before include "Breach" , "outrage" , "Infringement" , "Offence" , "abuse" .)