Something will do means something will solve the problem. But you still don't know for exact what it is.

something will do means anything will be helpful. A: I am very hungry B: What you want to eat? A: something will do. ie give me any food, it will be helpful. hope this helps. :)

Hi Coco. I'm not quite sure what you mean by "as title". Sometimes if you say, "it will do", it means "is sufficient" or "is enough". Example: "If you want to get rid of your headache, 2 aspirin will do." That means 2 aspirin are enough.