I did colonoscopy and it was clear, but a biopsy was done..am really confused if its clear then why the biopsy needed?should i be worried?plz help

No, don't worry: If you were told it is clear, then don't worry! your doctor probably biopsied some polyps, which are benign growths. They can change over many years to become cancerous, which is why they are always removed. Or maybe you had some signs of inflammation and your doctor wants a closer look. Biopsies are very common during colonoscopy, and it doesn't mean you have cancer!