Coaster (4)
'coaster' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for sled that I've seen before include "Snow transport" , "Tray on which to slide" , "Goods vehicle" , "Sledge" , "Toboggan (mainly US)" .)
(Other definitions for mat that I've seen before include "Piece of material for wiping feet on" , "Small rug" , "Unglossy floor pad" , "carpeting" , "Small protective floor-covering" .)