clench
To clench something is to hold onto it very tightly with the teeth or with the hands, or the upper and lower teeth are held together tightly.

- Jeremy clenches his teeth at night, but he doesn’t realize he’s doing it.
- Some people clench their teeth when they are angry.
- Through clenched teeth, the man said he would get even with the person who vandalized his house.
- When an alligator uses its teeth to clench onto an object or another animal, it doesn’t let go easily.
- The dog has a ball clenched in its teeth.
- The boy clenched his fists in preparation for a fight. (fist = fingers curled up in a ball)
- Clenched in Maria’s hands was the money that she needed to pay her rent for the month.
- Some drivers clench the steering wheel as they drive through ice and snow.