Runners smooch when son moves into the lead (4)
I believe the answer is:
skis
'runners' is the definition.
(ski is a kind of runner)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for skis that I've seen before include "Snow runners" , "Travels on snow" , "Engages in a winter sport" , "More than one runner" , "On these in slalom" .)