That is perfectly repairable but not with a mole grip, spanner or pliers. The reason I say that is because all these tools introduce a secondary dent where the pushing jaw fulcrums on the rim. It leaves a mark that causes pulsating brakes.
You need to bang out the dent from the inside. You need an anvil of sorts with a sharp, not rounded edge - 90 degrees. Have a helper hold the rim edge flat on the anvil so that the edge of the rim lines up with the edge of the anvil. Now hammer it with single, sharp blows so that the dent is flattened against the anvil. You can use a broomstick but it will break quickly and you may have to saw it off and bang again. The best tool is a 20m nylon rod about 200mm long and flat at the end. These rods can be purchased from engineering plastic suppliers. For the DIYer, a piece of broomstick will do.
Never use wood as an anvil. This will allow the rim to bend outwards i.e. too far.