Left a couple of directions in track (4)
I believe the answer is:
lane
'track' is the definition.
'left a couple of directions in' is the wordplay.
'a couple of directions' can mean two substitutions for 'direction'.
'left' says the letters should be written backwards.
'direction' becomes 'N' (compass direction north).
'direction' becomes 'eal' (I can't explain this - if you can you should believe this answer much more).
'in' means one lot of letters goes inside another.
'n' inserted into 'eal' is 'enal'.
'enal' in reverse letter order is 'LANE'.
Can you help me to learn more?
(Other definitions for lane that I've seen before include "regularly travelled route?" , "Byroad" , "Single line of traffic" , "Narrow street" , "Small road" .)