How to cut off objects outside the grid

Hi Kate,

Peter's answer is totally correct. It sounds like you may be newer to InDesign so I thought I'd explain a few more details/the why behind some of it. The grid is mainly there as a guideline for you, but in itself, it will not cut anything off. Fortunately, it's easy to set up a "Frame" which basically acts as a cropping tool (in design, this process is called "Masking").

If you look in the list of tools, you will see what is called the "Rectangle Frame Tool" (it's the one on the bottom here). You can drag this to be the size of the area you want to fill. This will create an area that will do what you are looking for – show whatever is inside it, and cut off whatever is not. 

Here's what it looks like when drawn.

You will then need to paste your objects inside of it. As Peter has mentioned, you will need to do something called "grouping" your objects to put them inside the frame. What grouping means is that InDesign will treat them all as one object. In order to do this, select all of your objects at the same time. Then you can either right-click and select "Group" from the drop-down list, go to Object > Group, or hit ⌘ + G / Ctrl + G. You'll notice that they start acting as one unit.

Then cut your objects to the clipboard (edit > cut, or ⌘ + X / Ctrl + X), select the frame you have created, and then click Edit > Paste Into. Your objects will now be inside the frame.

To move them around within the frame you can double-click on them and then drag them wherever you want, or resize them. You'll see if you move them to the edge, they will get cut off exactly as you hope. You can also change the size of the frame however you want and this will not resize the things inside it. 

You'll notice that if you place a photograph in InDesign, the same principle comes into play, with the photo living inside a frame.

Let me know if you need any further clarification! 

First select your objects and group them. then cut to the clipboard.

Draw a new frame the shape you want for the outer border of your cropped shapes with no stroke or fill, and while that is selected  choose Edit > Paste Into