No real significance, just a silly thing Santa (I) started doing for my kids. My kids have always loved Clementines and they're always the best this time of year. They were really into them when the oldests were prob 2 and 3yo. I have a old-fashioned picture in my mind of Saint Nick filling shoes with candy canes and fruit. I guess that's where I got the idea. They think it's kinda cool or funny. Like a quirky thing santa does at their house.
This year, we tied a ribbon across the top of the stairs to remind the early risers not to go downstairs (until everyone was awake). But they could see the clementines scattered on the stairs, so they knew Santa had come!