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?
Let a hot pepper (jalapeño or habañero, perhaps) soak in your liquid for however long it takes to achieve the desired hotness.
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
Szechuan (Sichuan) pepper husks can be brewed/simmered in hot water and results in a relatively clear broth that can be very "hot" and a much more interesting taste than refined or artificial capsaicin
It also has that numbing effect that most people find rather interesting
Cajohn's Frostbite it is a clear hot sauce and pretty good for making mixed drinks
I have some habanero powder that has a beige color. I would imagine that wouldn't discolor a clear liquid too much. And believe me, a little bit goes a long way.
Fresh uncooked Ginger paste has quite a kick to it, as does fresh ground Horseradish. The tastes are not much like capsicum, but can be eye-wateringly potent.
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.