  We study the mixing effect for a generalized Keller-Segel system with
degenerate dissipation and advection by a weakly mixing. Here the attractive
operator has weak singularity, namely, the negative derivative appears in the
nonlinear term by singular integral. Without advection, the solution of
equation blows up in finite time. We show that the global well-posedness of
solution with large advection. Since dissipation term degenerate into the
damping, the enhanced dissipation effect of mixing no longer occurs, we prove
that the mixing effect can weak the influence of nonlinear term. In this case,
the mixing effect is similar with inviscid damping of shear flow. Combining to
the mixing effect and damping effect of degenerate dissipation, the global
$L^\infty$ estimate of solution is established.
