A few years ago, I found a video of Emerson, Lake, & Palmer performing "Take a
Pebble" live on German television. Near the end of the performance, Emerson plays a Clavinet L:
The studio recording of "Take a Pebble" doesn't
feature Clavinet, however.
I don't have all of the ELP albums, but of the ones I do have, the only songs that include Clavinet are "Tank" on Emerson, Lake, and Palmer and various live recordings of "Nutrocker." Here's a video of "Nutrocker" performed live in Switzerland in 1970: