A crossfade implies you are using two tracks and fading from one to another. If you are trying to eliminate a portion of a track and cross fade the two pieces then you need to split the track turing it into two tracks which you can crossfade together and then export as a single file.
All crossfade work needs to be done in multitrack screen. This cannot be done in waveform screen. Different workflows for the two screens. Multitrack screens are where you can do any type of editing/work. Waveform screen is limited to only certain features for editing. To delete a portion and crossfade. Select track you are working on....place marker, right click select split. Move marker to end point of section you are wanting to cut, place marker, right click select split. you can now delete that center section and crossfade the two remaining splits. Export wave as desired. OR Bounce to new track, open track in waveform and save. Depends on your personal workflow and desired results which way you approach things