Question

How can light be produced by accelerated electrons as they remain as wave and can not be accelerated ?

Answer 1

The electrons intrinsic properties are their electric charge and their magnetic dipole moment. ... Since there is no decrease of the speed of a constant moving electron there wouldn't be any loss of energy, hence the electron does not radiate. So you are right that only particles under acceleration radiate.
A photon of light does not accelerate to lightspeed. Rather, a photon is already traveling atlight speed c when it is created. It's not like a photon jumps from a speed of zero to lightspeed instantaneously. Rather, a photon is always traveling at c, from the moment of its creation.