a grip on
grip on (something)
1. A good physical hold on something. In order to remove the bolt, I needed to get a grip on the wrench.
2. A newfound understanding of a topic or concept. The teacher spent extra time going over the material in class because she wanted her students to have a good grip on the subject matter before they took the exam.
*a grip on something
1. and *a hold on something Lit. a good grasp on something. (*Typically: get ~ have ~ give someone ~.) Try to get a grip on the ropes and pull yourself up. You should get a hold on the knob and turn it firmly.
2. Fig. a thorough knowledge of some topic. (*Typically: get ~ have ~ give someone ~.) I need to have a grip on the basics of accounting. Try to get a hold on all the facts first.