In this paper, an efficient Cyclic Prefix (CP) reconstruction scheme is proposed for Single-Carrier systems with Frequency-Domain Equalization (SC-FDE) that employ insufficient length of CP at the transmitter. By utilizing a decision feedback filter to cancel the residual InterSymbol Interference (ISI) in the equalized signal, the proposed scheme can effectively lower the low bound of performance for the CP reconstruction schemes and can greatly improve the Bit Error Rate (BER)performance of SC-FDE systems. In addition, the existing methods and the proposed scheme are also optimized. It is shown in the simulation results that, when the Signal-to-Noise Ratio (SNR) exceeds a certain threshold, the proposed scheme can achieve the low bound of performance for the existing methods. Moreover, by increasing the number of iteration or through optimization, the low bound can be outperformed.