The structure of the 18O nucleus at excitation energies above the $ α$ decay threshold was studied using 14C + $ α$ resonance elastic scattering. A number of states with large $ α$ reduced widths have been observed, indicating that the $ α$ -cluster degree of freedom plays an important role in this N$ \ne$Z nucleus. A 0+ state with an $ α$ reduced width exceeding the single-particle limit was identified at an excitation energy of 9.9±0.3 MeV. We discuss evidence that states of this kind are common in light nuclei and give possible explanations of this feature.