Thomas, I didn't like this clue - the 'international lawyer' stuff seemed a bit ...wayward.
The answer is just a phrase meaning 'I'll get my revenge', 'You're for it now' and so on.
Matador, I rather think Valms , in post 5, was offering a "hint" to Thomas, not asking for help!
I had exactly the same reaction when I solved the clue on Sunday!