  We theoretically investigate the interplay between local lattice distortions
around $\rm{Mn^{2+}}$ ion impurity and the ion's magnetic polarization,
mediated through spin-orbit coupling of hole. We show that the tetrahedral
symmetry around $\rm{Mn^{2+}}$ ion impurity is spontaneously broken even in the
paramagnetic regime. Modest local lattice distortions around the impurity
$\rm{Mn^{2+}}$ ion, along with the growth strain, stabilize magnetization along
$< 110 >$ directions, in the ferromagnetic regime. We explain the
experimentally observed in-plane uniaxial magnetic anisotropy seen in this
system using this symmetry-breaking mechanism.
