  We study the parity-violating alpha+d decay of the lowest 0+ state of Li-6 in
a microscopic three-cluster model. The initial bound and the final scattering
states are described consistently within the same model. The parity-violating
decay width is calculated in perturbation theory using the parity-nonconserving
nucleon-nucleon interaction of Desplanques, Donoghue, and Holstein (DDH). We
find that the decay width is sensitive to dynamical degrees of freedom which
are beyond the alpha+p+n model, for example, alpha excitation and breakup. In
our full model, which contains breathing excitations of the alpha particle and
H-3 + He-3 rearrangement, the parity-nonconserving decay width is
Gamma=3.97x10^{-9} eV, using the DDH coupling constants.
