Jog, say, with horse heading north (5)
I believe the answer is:
nudge
'jog' is the definition.
(I know that jog is a more specific form of nudge)
'say with horse heading north' is the wordplay.
'say' becomes 'eg' (both can mean 'for example').
'with' says to put letters next to each other.
'horse' becomes 'dun' (I've seen this before).
'heading north' is a reversal indicator (in a down clue, letters go up).
'eg'+'dun'='egdun'
'egdun' in reverse letter order is 'NUDGE'.
(Other definitions for nudge that I've seen before include "Give a reminder" , "suggestive move" , "Gentle poke with elbow" , "A gentle reminder?" , "Remind, prompt gently" .)