The blue-shaded section at the rocket's base is the recoverable portion of the vehicle that is supposed to return back for landing and re-use, since it contains the engines which are the most expensive component that needs to be saved. With ISRO also trying to begin development on reusable launch vehicles, they also need to look seriously at the vertical landing concepts like the Rossiyanka concept design above, instead of just winged landing designs. Wings add a lot of weight and drag on the way up, relative to the aerodynamic benefit they provide on the way down.
When considering a vertical-landing reusable rocket, ISRO should give serious thought to designs like this Russian one, with an eye to landing them in the Andaman Islands after launching from Sriharikota. Note the wider cross-section and squatter aspect-ratio of the reusable bottom section, which might afford a better cross-range glide capability to make it to the Andamans for landing. Space launches are always in an easterly direction, and hardly any countries have the convenience of a less-populated easterly island wing at a distance from their mainland like India does, to serve as a landing point for a recoverable vehicle. Advantages like this can help rockets save fuel mass, which could give India an unbeatable advantage.