Clementines have been such sweet sellers this year that some smaller US grocery store firms found themselves left out of this fruit's distribution loop from Spain. While many grocers say the small mandarin-type orange is becoming a new US staple, others say demand is slack. However, US imports have been rising sharply for what was once nothing more than a Christmas stocking-stuffer in isolated areas of the country, according to the US Department of Agriculture. There seems to be a bigger supply of clementines this year nationwide as well as across the Fort Worth/Dallas area.