I have two switches at the bottom of my stairs in the basement. One switch is a three way to the switch at the top of my stairs. The other switch lights a series of lights all connected to the same circuit. One of those lights is in the pantry and what I would like to do is isolate that light from the rest by adding a single pole switch to the room. The switch at the bottom of the stairs would still light up the rest of the lights.
Whether you can simply break that light off the circuit and put it on a new switch depends completely on how the power is run.
However if the power comes through the existing switch then no you will have to run a new feed to the light. That feed can go through the new switch (shown in the bottom diagram), or straight to the light whichever is easier.
Who said MS paint couldn't be used for wiring diagrams...