  A practical scheme is proposed for creation of continuous variable entangled
cluster states of four distinct atomic ensembles located inside a high-finesse
ring cavity. The scheme does not require a set of external input squeezed
fields, a network of beam splitters and measurements. It is based on nothing
else than the dispersive interaction between the atomic ensembles and the
cavity mode and a sequential application of laser pulses of a suitably adjusted
amplitudes and phases. We show that the sequential laser pulses drive the
atomic "field modes" into pure squeezed vacuum states. The state is then
examined against the requirement to belong to the class of cluster states. We
illustrate the method on three examples of the entangled cluster states, the
so-called continuous variable linear, square and T-type cluster states.
