Auditor's foundation course (5)
I believe the answer is:
route
'course' is the definition.
(both can mean a path)
'auditor's foundation' is the wordplay.
'auditor's' shows a homophone (sound like).
'foundation' becomes 'root' (I've seen this in another clue).
'root' sounds like 'ROUTE'.
(Other definitions for route that I've seen before include "Course of journey" , "track" , "Way, course" , "Course of 7" , "Choice of roads in an itinerary" .)