We report on a theoretical study of a dz2 surface state at the tungsten (110) surface, addressing in detail the spin-resolved electronic structure as well as photoemission spectroscopy. In agreement with recent experiments, this surface state shows a strongly anisotropic dispersion: in the H-Γ-H direction of the surface Brillouin zone, it disperses linearly but becomes flattened along the N-Γ-N direction. The ab initio calculated spin texture agrees with the one derived from a model Hamiltonian; due to twofold surface symmetry and time-reversal symmetry, the out-of-plane spin polarization vanishes. The photoemission intensities depend sensitively on the polarization of the incident light, because of the orbital composition of the surface state. The photoelectrons become spin-polarized out-of-plane, which is attributed to breaking the timereversal symmetry by the excitation process.