You have changed your name after graduation that is well understood but what about your credentials, have you changed your name in your educational certificates, Aadhaar card, driving licence, PAN card, ration card, credit card, debit card, voter card also? If yes, go ahead. There is no problem. If no, you are inviting big problems for your future educational and career pursuits.
Changing name is not a joke. It will create lot of problems because your new name will not be seen on your old certificates and mark sheets. One immediate solution is revert back to your old name and you will be in safe zone. There will be no mismatch and you will sail ahead comfortably. What legal action you have taken for changing your name. May be an affidavit and advertisement in newspaper. Undo all those actions and appear in UPSC exam with your old name. You can change it later when you are settled in life and there is no future exam or interview for you. Take legal advise and act fast to undo the childish thing inadvertently done by you.
Knowledge is power.