Surface of cycle path . . . (5)
I believe the answer is:
outer
'surface' is the definition.
(I've seen this in another clue)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for outer that I've seen before include "Route (anag.)" , "External kind of route" , "Ring for double scores on a dartboard" , "Archer's shot" , "External; peripheral" .)