Possible workarounds:1. Do a Definition Query to only show the features that lie within the boundary2. Select by Location > select the features from all layers that are within the boundary > export those features out to a new shapefile or feature class3. Convert the labels to annotation, then manually move them within the clipped boundary4. If clipping to the Current Extent: -zoom in so the labels aren't over lapping -set a reference scale and lock the labels -you can now zoom in/out and pan without having the labels moving