Rough path (5)
'rough path' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for trail that I've seen before include "Need to catch up with" , "Track or mark left by something that has passed" , "Beaten path; track" , "Beaten path; be in losing position" , "Scent or track followed in hunting" .)
'rough path' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for track that I've seen before include "Shadow" , "Chase - dog - tail" , "Trace; path" , "Way" , "Rough path or road" .)