Make a solid inside the container to represent the water. Use Shared Topology to avoid using Bonded Contact. Create a new material called Water. Use the properties for water that I used in this post:
This works for a statics simulation but the top of the water won't find a new level if the clamp deflects by a large angle, you would have to adjust the angle of the top of the water solid after you solve it once, but the water will push out on the sides of the container because the water material properties have no shear stiffness.