Trending @Capgemini; Advice needed

I have received an offer from a good stable product based company. But currently my client is the child company of the company I received offer from. Though both companies are now separated legally and operate independently. There is a clause in my offer letter that we can not work directly with client company/ CG prospect clients/associates. Is it a clause breach if I join the company? Or how should I get this clarified so that there are no repercussions later from CG or other company side? Looking for genuine replies only.