This carries the track by way of a pipe (7)
I believe the answer is:
viaduct
'this carries the track' is the definition.
The definition suggests a singular noun which matches the answer.
'by way of a pipe' is the wordplay.
'by way of' becomes 'via' (via means by way of or by means of).
'a pipe' becomes 'duct' (I've seen this in another clue).
'via'+'duct'='VIADUCT'
Can you help me to learn more?
(Other definitions for viaduct that I've seen before include "Rail bridge over valley" , "Road/rail bridge" , "Kind of road over a road" , "Long bridge over land" , "Bridge-like structure" .)