Stop running up and down (4,2)
I believe the answer is:
pull up
'stop running' is the definition.
'pull up' can be an answer for 'stop' (pulling up is a kind of stopping). I am not certain of the 'running' bit.
'up and down' is the wordplay.
'and' is a charade indicator (letters next to each other) (I've seen this in other clues).
'down' becomes 'pull' ('pull down' can be a synonym of 'down'**).
'up' after 'pull' is 'PULL-UP'.
(Other definitions for pull up that I've seen before include "Exercise" , "park" , "Stop or cause to stop" , "Take to task" , "Halt" .)