Traffic marker (4)
'traffic marker' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for cone that I've seen before include "Solid figure" , "Ice-cream cornet" , "Tapering object" , "Shape, the base is a circle and the sides taper up to a point" , "children can lick" .)
(Other definitions for pylon that I've seen before include "Power cable support" , "Power cables supporter" , "Electric cable support" , "Tower or tall post" , "Power-cable support" .)