Follow the trail (5)
I believe the answer is:
track
I believe this clue is a double definition.
'follow' is the first definition.
(I know that track is a more specific form of the action follow)
'the trail' is the second definition.
('track' can be a synonym of 'trail')
(Other definitions for track that I've seen before include "Extract from record" , "Path; rails; circuit" , "One of the songs on CD?" , "Follow < course" , "Number on CD" .)