Well…you don’t. At least not as far as I know. It’s one of the great mysterys of life that you can drag a precompute into the source monitor from a bin but can’t source it back from the timeline.
If you just need to cut the key into another spot on the timeline and don’t want to spend the time searching for the original, mark it in the sequence and sub it out to a bin. The sub-sequence will function the same as the original clip.
If you actually need to find the original, put on your hip waders or hope that somebody here knows something that I don’t (I’ll be watching and hoping).
This is why each of my projects gets a dedicated “titles and fx” bin out of the box.
The Rat