Clipped Wing Mustang
The results will be a higher wing loading unless you reduce the weight in proportion to the wing area reduction. Increasing the wing loading will increase the stalling speed in proportion to the square root of the wing loading increase. This will extend the take off run a bit and make take off and landings a bit faster. Reducing the wing span should increase the roll rate. Reducing the aspect ratio should steepen the landing approach a little with the throttle at idle.