  The light amplification by finite active media is used extensively in modern
optics applications. In this paper the light amplification and scattering by
cluster of small particles is studied analytically and numerically with the
help of the local perturbation method and phenomenological laser theory. It is
shown that light amplification is possible even for one small particle, and
that the amplification is more profound when the light frequency nears the
frequency of the cluster's morphological resonance. Theoretical discussions are
supplemented by numerical results for scattering by clusters which particles
positioned at ordered and at slightly disordered positions.
