Possible to crop to page Indesign?

It also can be done using pathfinder:

Speaking strictly of the mechanics, you could select all, cut, then Paste Into a page-sized frame. But doing that would accomplish nothing useful. On the contrary, it would eliminate required bleeds, land everything on a single layer, make it much harder to edit, and perhaps further exacerbate some of the layout errors evident in your design.

If you needed to, you could probably do it like this (all objects to be cropped need to be on one layer).

1. Choose Edit > Select All, the choose Object > Group so everything you have is in one grouped object.

2. Create a layer above this group, and create a rectangle the trim size of the document page.

3. Select the group you created and Edit > Cut to put it on the Clipboard.

4. Select the trim size rectangle, then choose Edit > Paste Into.

There's no single command that will trim oversize objects or bring their frame edges in to the page border, but you can do the latter manually.

And, of course, switching to Preview view will show only the active page contents.

Other than having an exceptional case of the 'neats,' I don't think there's much need of such a feature — such cropping is inherent to all printing and export operations. Do you have some specific reason for needing or wanting it, besides just cleanup of the designer view? (ETA: Something I can't fault at all... I hate a sprawling mess around my work, even if I 'know' it will go away in the export...)