(informal American) broadly, assistance in the form of money or resources provided to a person or enterprise, often to help the launch under the promise of sharing the resulting profits;
e.g. They furnished a grubstake to help him get his business started.
(verb)
to provide a person/enterprise with assistance in the form of money or resources, usually in order to help them launch with the promise of sharing resulting profits;
e.g. She offered to grubstake my project because she liked its premise.