The consecutive procedure for the calculation of a size dependence of an electron affinity to a large dielectric cluster of radius R is presented. The perturbation theory over the small parameters (r) over bar /R and L/(r) over bar (L is the scattering length in the condensed medium, (r) over bar is the interatomic distance) is proposed for an electron binding energy in the frame of effective medium approach, using the theory of state of light quantum particle in a cellular medium. Estimations are fulfilled far liquid xenon clusters.