We determined the evolution of the main-chain conformation and of the liquid crystalline structure of a liquid crystal polymethacrylate in the smectic phase, versus shear rate. It is shown that the macroscopic shear was transmitted to the smectic layers which ensured an efficient shear of the polymer main-chains. The outcome was a macroscopic orientation of the smectic monodomains with the smectic planes parallel to the shear plane. The polymer main-chains already confined by the mesogenic layers, were in addition, the more elongated along the velocity direction that the stronger, the shear was. These results were obtained in situ by the observations in the shear plane and in the vorticity plane.