If it's the hot water valve and your cold water supply to your water heater has a shut-off valve, you can shut that valve off for the hot side only to repair the hot water shut-off valve at the tub. If that shut-off valve leaks, then you will have to shut off the main.
Depending upon the type of hot water shut-off valve you have at the tub, you may be able to easily repair it with a new washer on the end of the stem, or you may need to replace it.
Good luck!
Mike
Depending upon the type of hot water shut-off valve you have at the tub, you may be able to easily repair it with a new washer on the end of the stem, or you may need to replace it.
Good luck!
Mike