Jump over (8)
I believe the answer is:
leapfrog
'jump over' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for leapfrog that I've seen before include "Jump over" , "Children's game in which one jumps over the other alternately" , "Child's game of jumping over other children" , "Overtake in position" , "Children's game of jumping over each other" .)