I want to prepare a drink that is hot (spicy) but I don't want to use regular hot sauce because it will affect the color. Is there anything like "clear" hot sauce?
Hmm, I'd look for pure Capsaicin if all you want is the heat. It's colorless/odorless so could work, but I'm not sure where you can find it.
I've heard of white, hot sauces which may work for you, here is an example
Cajohn's Frostbite it is a clear hot sauce and pretty good for making mixed drinks
There's a style of hot sauce that is basically whole peppers soaking in a vinegar solution; it's probably work, but it'd give a sour note from the vinegar.
You could always make your own ... it tends to be made with green peppers; I'm guessing green or yellow would impart less color.
Also, a quick search suggests that there's at least two brands of 'clear hotsauce' out there -- Panola and Frostbite.