We report the structural and relaxation investigations of an achiral bent-core compound in SmAP(A) phase. The studied material undergoes transition from one biaxial state to the other via a uniaxial state under electric field. These transformations are explained as successive transition from antiferroelectric to ferroelectric states, where, the intermediate uniaxial state has the molecular secondary directors in the neighbouring smectic layers perpendicular to each other. We also found that near SmAP(R) to SmAP(A) phase transition the second harmonic electro-optic response, induced polarization, and the dielectric behaviour hint softening behaviour in the material.