  Second-class weak currents can in the standard model be induced by chiral
symmetry breaking. In the specific case of the decay tau-->omega pi nu_tau,
dominated by the first-class vector current with the rho quantum numbers, such
effects would manifest themselves by small axial vector (or, generally,
non-vector) contributions to the decay rate. We present an attempt to estimate
such effects, based on a vector and axial-vector dominance model of the
relevant matrix elements supplemented by omega-rho mixing. We also give an
indication on the amplitude directly mediated by b_1(1235)-->omega pi, in
principle also allowed in the standard model by isotopic spin violation.
