What does it mean? This informal phrase basically means to try to do something that could be a little difficult.

Is it positive or negative? Neither. It’s neutral, but it does show you tried or are going to try.

When do you use it? It’s used when you say you’re going to try something/have tried something/or tried something that was a little difficult.

Example 1: The shower broke, I had a crack at fixing it, but couldn’t.
Example 2: Next year I’m thinking of having a crack at a marathon.
Example 3: You still haven’t fixed it? Let me have a crack.

Question: What would you like to have a crack at that could be challenging?