Hello, thanks for answering my previous question.
Not that I am aware of. If you are using the 4.x api you can set map contraints but not actually clip the basemap.
The poor man's way of doing this would be to make a polygon dataset of the entire world and "burn" in the boundary of your country of choice. Publish a service where the country has been removed via queryDefinition and then symbolize the remaining polygon (the rest of the world) using a white fill. When adding that service to your map, make sure that it is at the bottom layer of your JS map and now you have a basemap clipped to a county's boundary.
Retrieving data ...