You can crop or split selected line features to a selected area feature by right-clicking and selecting the option to Crop/Split Selected Lines to Selected Areas. This will delete any portion of the line feature that lies outside of the selected areas unless you select the Split option, in which case separate lines will be created for the parts inside and outside the selected area feature(s). Note that the original line will remain available as a deleted feature, so you can recover the original line if needed.