  We consider the impurity problem in an orbital Feshbach resonance (OFR), with
a single excited clock state $|e\uparrow\rangle$ atom immersed in a Fermi sea
of electronic ground state $|g\downarrow\rangle$. We calculate the polaron
effective mass and quasi-particle residue, as well as the polaron to molecule
transition. By including one particle-hole excitation in the molecular state,
we find significant correction to the transition point. This transition point
moves toward the BCS side for increasing particle densities, which suggests
that the corresponding many-body physics is similar to a narrow resonance.
