Let’s talk about the downswing and your lead arm. A good reference point is to have the lead arm inside the target line around 20* at lead arm parallel (P5) in the downswing. Little more inward could help be more of a draw pattern where more outward could help with a cut pattern. Here is a good drill to give you a visual and feeling. YouTube Link
If you don’t have someone to hold an allotment rod or club just outside your trail shoulder use a shaft with an alignment rod in it or two alignment rods taped together. When using the alignment rods place the rod outside the ball line and have it go through your trail shoulder like on the featured image above.
Now that you know how to set it up let’s take a look at what it does. If your lead arm moves out too fast it will run into the stick. The alignment rod also gives you a spacial reference of where the lead arm and hands have room to operate. Start off with small shots and success then speed up the swing. Below is an image keeping the lead arm in on the left and one where the lead arm worked out too fast on the right.
Click here for the YouTube Link or copy and paste this link in a browser window: https://youtu.be/JxdhnZSRqEA