Can CAT be cleared in the first attempt?

Yes, CAT can definitely be cleared in first attempt.
All you need is a good study-plan, solid grip on the basics, and a minimum of 30 mocks (with thorough analysis). Try to stick to your studyplan as much as possible, and have a good peer group / mentor while preparing. If you can follow these steps well, clearing CAT in first attempt is not a tough deal. All the best.