I have a clivia about twelve years old that looked like this one year when I procrastinated too long in the Fall, and didn't bring it in until a light frost hit it. I just trimmed back the leaves to the healthy part, and saw no ill effects. To be on the safe side, in case this is not the problen, I would moisten a cotton ball or cloth with alcohol and wipe off my cutting tool after each cut and dispose of the leaves in the trash, and not in a compost bin.

I had similar freeze burn of leaves. I was advised by experts to leave them alone until they become brown. In the spring you can then cut the damaged areas and treat the cut areas with fungicide as they otherwise will weep. Good luck. Buy some frost protection covers to help just in case there is a repeat next year. I just ordered more...to be on safe side! mary