Cognitive radio technology is introduced to identify the spectrum holes dynamically. Such dynamic spectrum access operations cause the nodes in the cognitive radio sensor networks (CRSNs) into energy depletion problem. To handle this problem or to utilize the entire network's energy efficiently, clustering is found as one of the best solution. Even though uniform clustering mechanism reduce the energy consumption but it is not suitable when the network node density increases. Hence, this paper proposes a new clustering mechanism called as energy and spectrum aware clustering routing protocol (ESCRP) for CRSNs. Initially, the entire network is clustered nonuniformly into several clusters. Next, energy, channel availability rate, geographical and temporal correlation metrics are used to select the cluster head (CH) for each cluster. Finally, the collected information from each CM is transferred to the sink node through multi-hop communication between CHs. Extensive simulation experiments are carried out over the proposed ESCRP and the performance is measured with several performance metrics including Network lifetime and average energy consumed. From the experimental results, we observed that the weight combination 𝛼 =