To do Alt + N S C C on Mac in Excel, download and install Accelerator Keys, then press Option, followed by N, S, C, and C.
Command: Screen Clipping
This is how to do Alt + N S C C on Mac in Excel with Accelerator Keys, the native ribbon and alt key shortcut solution for Mac users who get more done with Excel.
Alt + N S C C activates Screen Clipping mode where you can draw a rectangle to capture any portion of your screen. Excel minimizes temporarily, letting you select the area to clip, then inserts the captured image into your spreadsheet.