VERGE ON means ‘to come close to’.
I am fed up. I am verging on quitting my job.
The pound is verging on an all time high against the euro.
This project is a bit of a joke. It is verging on the ridiculous.
VESTED INTEREST means that you have a personal stake.
I have a vested interest in improving the quality of this school. My children are students here.
She will probably join us if we give her a vested interest in our business.
You had a vested interest in giving him the contract. He is your brother.
A VICIOUS CIRCLE is where attempting to solve a problem ends up making the problem worse.
The poor cannot afford good education and, in a vicious circle, remain poor.
He is in a vicious circle of dieting followed by gaining weight.
Treating neuropathy can start a vicious circle of other medical problems.