The ever-increasing spectrum demand in wireless communication networks like Sensor Network has routed to the development of Cognitive Radio Sensor Networks (CRSN). Securing the CRSN against the Primary User Emulation Attack (PUEA) plays a crucial role in the current research. In this paper, we propose an Opportunistic Transmission using the Hybrid Sensing method for the CRSN in the presence of smart PUEA. In Hybrid sensing method, both proactive sensing and reactive sensing techniques are effectively combined to reduce the error probability in detecting the Primary User signal. Furthermore, we have overcome the effect of PUEA by using the Opportunistic Transmission to improve the throughput and energy efficiency of the SU network. Both simulation and Software Defined Radio (SDR) based hardware test bed results show that the throughput is increased by 18%, the energy efficiency is increased by 11% and the error probability is reduced by 20% compared to the existing method.