  In this present paper, we investigate a new class of singular double phase
$p$-Laplacian equation problems with a $\psi$-Hilfer fractional operator
combined from a parametric term. Motivated by the fibering method using the
Nehari manifold, we discuss the existence of at least two weak solutions to
such problems when the parameter is small enough. Before attacking the main
contribution, we discuss some results involving the energy functional and the
Nehari manifold.
