Roundabout route (5)
(Other definitions for orbit that I've seen before include "revolutionary course" , "Circle - influence" , "Rotating path" , "field of activity" , "Planet's course" .)
'roundabout route' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for detour that I've seen before include "Indirect route" , "A way round, say, road works" , "Deviation from direct course" , "Temporary route" , "Deviation from the usual route" .)