Spectrum sensing is used to detect the unexploited sub-bands in the radio environment. In order to improve the accuracy of the spectrum sensing, the cooperative spectrum sensing method is assumed to be the best method to be used. However, it consumes power by exchanging the sensing results among the participating nodes. An efficient cooperative spectrum sensing method is proposed in this paper to save the power consumed in spectrum sensing results' reporting. The clustering method is used to divide all the cognitive nodes in a specific number of clusters. Each cluster has a cluster head (CH) which is responsible for collecting data from different cognitive nodes in the same cluster and sending the cluster's decision back to them. After each cluster head receives the clusters' decisions, the final decision is made. Simulation results show that the proposed method helps in power saving in comparison to the traditional method.