Thanks guys it's really wonderful expression. i think i could use it more often with more confidence.

"don't cut it anymore" (using more than one excuse) or "doesn't cut it anymore" (if using only one excuse) not acceptable not good enough (like not a good enough excuse) Usually implies someone has been getting out of doing something, using an excuse, and now that just won't work -- they have to face the task, not get out of it. Sometimes it implies the person is lazy, just looking for excuses to get out of doing something. Other times it's said to motivate someone to try something they didn't believe they could do because everyone else knows they can do it if they try. It could be said to someone who is trying out for a part in a play or movie. "Sorry, your dancing just doesn't cut it. We can't use you in this play!" Or someone trying to become a radio announcer. "Sorry, your voice just doesn't cut it." (Your voice isn't good enough). I just added this to Cate's comment to give you a few more examples to help you put it in context.

It's an idiom, so it doesn't make sense word for word. I'm not sure where it comes from, but it means excuses don't work, they don't cut it or aren't effective, don't work in some situations. Youcan't get away with saying you're too young, you don't know how, etc, when all that matters to anyone is if you can do the job. A related idiom is "can't cut the mustard". Which again means ineffective. Don't know where that one came from, either!