on the apparent horizon with RA, the radius of the apparent hori-zon. Further, they have shown the equivalence between the ther-modynamical laws and modified Einstein field equations in Gauss–Bonnet gravity and more general Lovelock gravity. Subsequently Cai et al. [18–20]have extensively studied unified first law in FRW universe not only for Einstein gravity but also in Lovelock gravity, Scalar–Tensor theory [18]and Brane-world scenario [20]. In this context, Eling et al. [22]have shown for f(R)gravity theory that there should be entropy production term in the Clausius relation and it can be associated to shear viscosity of the horizon in pure Einstein gravity. Very recently, thermodynamical laws have been studied [23,24]in f(R)gravity as well as in generalized f(R)grav-ity with a modified version of the entropy of the horizon. In the present work, we have modified the horizon entropy suitably so that Clausius relation is automatically satisfied.