...
- In the analysis tab, click on Tools and search for Clip in the Geoprocessing pane. You want the one in (Analysis Tools).
- Open the Clip tool, and put the feature you want to clip as Input Feature. For the Clip Features, click on the
click rectangle one, also show how to do the straight right angle thing
if you need to make a mistake and want to make adjustments, it's probably easier to delete it and draw it again to make a new polygon feature that contains the region you are interested about. Then click run. - The clipped Input Feature will be exported as a new feature class showed in the Content Pane.
...