Type-I clathrates are of active interest for thermoelectric applications at temperatures above room temperature. This is mostly due to rattling modes of the guest atoms in these cage compounds which lead, by interaction with the acoustic phonon modes, to very low lattice thermal conductivities. Recently, the first Cerium-containing clathrate, CeBa7Au6Si40, was discovered by our group. At 600 K, it shows a 100% enhancement of the thermoelectric figure of merit ZT over a Ce-free reference compound. As mechanism of this extraordinary effect, a Kondo temperature TK of several 100 K was proposed to exist in this material, in addition to a low-temperature Kondo scale of about 1 K. We propose here to carry out inelastic neutron scattering measurements on CeBa7Au6Si40 to test the proposed claim of a dual Kondo temperature by measuring crystal field excitations.