There are several approaches to export only the clips of choice:
Apply standard markers on your clips.
Note: markers are only recognized, if they are applied to clips on the primary storyline!
In the clip export settings check "Export only clips with" and choose Standard Markers, To-do Markers, Completed Markers or Chapter Markers.
Also, choose "Discard disabled clips" if you do not want to upload disabled clips.
Big timelines take long to render. But you can drastically reduce rendering time if you're only interested in exporting a small of section. To share just a portion of a project, you must make a range selection. You can use the I and O keys to set the range start and end points or use the range selection tool.
Note: please make sure that the clips of interest are completely included in the selected range. Partially included clips are discarded.