Track electronic vehicle reversing by road (7)
I believe the answer is:
raceway
'track' is the definition.
('raceway' can be a synonym of 'track')
'electronic vehicle reversing by road' is the wordplay.
'electronic' becomes 'e' (as in e-mail or e-books).
'vehicle' becomes 'car' (car is a kind of vehicle).
'reversing' says the letters should be written backwards.
'by' means one lot of letters go next to another.
'road' becomes 'way' (I've seen this in other clues**).
'e'+'car'='ecar'
'ecar' written backwards gives 'race'.
'race'+'way'='RACEWAY'
(Another definition for raceway that I've seen is " Mill water channel".)