The bit error rate (BER) performance of single-carrier (SC) transmission in a frequency-selective fading channel can be significantly improved by using frequency-domain equalization (FDE). In a cellular network, however, the same frequency is reused in different cells to efficiently utilize the limited bandwidth and therefore, the BER performance degrades due to co-channel interference (CCI). Adaptive antenna array (AAA) is one of the well-known techniques to suppress the CCI. In this paper, we consider a frequency-domain AAA, based on the average CCI power minimization criterion, jointly used with FDE and theoretically derive the optimum array weight using Lagrange multiplier method. We evaluate, by the computer simulation, the outage probability of the BER in a frequency-selective CCI environment.