My suggestions would be to manually focus the lens to the middle of the orange, and with the high aperture number you'll be using, you'll get the front, back, and water all in nice clean focus.
Adjust your framing, perhaps try vertically shooting this since we are seeing the water come vertically crashing down into the orange?
Diffuse the flash, take LOTS of shots, and I guarantee you'll pull something very impressive out on your 3rd attempt.