You should be using a main form (clients) and a subform (jobs) linking client form (client name?) to job list (client name). It is easy to add job records to a client this way - not so much to a list box. You could use this main form to add clients as well.
I would not link jobs to clients by name. If client name changes (e.g. because of a business name change, marriage, whatever) you will have a problem. The time to do things right is now - it takes less time than it takes to fix it, and you end up with keeping more of your hair.
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.