Direct route following sun (4)
I believe the answer is:
sway
'direct' is the definition.
(thesaurus)
'route following sun' is the wordplay.
'route' becomes 'way' (way is a kind of route).
'following' means one lot of letters go next to another.
'sun' becomes 's'.
'way' put after 's' is 'SWAY'.
(Other definitions for sway that I've seen before include "Strong influence" , "Move from side to side; influence" , "Lean from side to side - influence" , "Swing from side to side, or influence opinion" , "Oscillate" .)