What insect is this? (India)
This is mostly a guess and loose suggestion, since the picture is not very clear (would need to see the larvae in more detail). However, Bagworm moths (Psychidae), Case moths (Coleophoridae) and Caddisfly larvae (Trichoptera, almost exclusively aquatic) all build similar cases. They construct their cases out if silk and often include debris, pebbles and other materials. I wouldn't be surprised if the larvae in your picture belongs to one of the first two taxa. Bagworm moths and Caddisflies generally include lots of external materials in their larval cases, which could point to Case moths for your specimen (which seems to have a weaker case mostly made of silk).

Here are two pictures of first a UK Case moth larvae (Coleophora deauratella) followed by a Bagworm moth (Dahlica triquetrella), just as comparisons. If you do google image searches of "group name + larvae" you will see many examples of what they can look like.



And just as a cool example - the larvae often use random material lying around to build their cases, which can give the following result, if caddisfly larvae are bred in a tank containing pieces if gold and pearls. For further information see this link.