  We study the transverse single spin asymmetry in Drell-Yan production in pA
collisions with incoming protons being transversely polarized. We carry out the
calculation using a newly developed hybrid approach. The polarized cross
section computed in the hybrid approach is consistent with that obtained from
the usual TMD factorization at low transverse momentum as expected, whereas at
high transverse momentum, color entanglement effect is found to play a role in
contributing to the spin asymmetry of Drell-Yan production, though it is a
$1/N_c^2$ suppressed effect.
