Collapsed in trek up a toll road (8)
I believe the answer is:
turnpike
'a toll road' is the definition.
(I know that toll road can be written as turnpike)
'collapsed in trek up' is the wordplay.
'collapsed' is an anagram indicator.
'in'+'trek'+'up'='intrekup'
'intrekup' with letters rearranged gives 'TURNPIKE'.
(Other definitions for turnpike that I've seen before include "American highway" , "Old toll-gate, or new road with toll stations" , "way in the US" , "where one pays one's way" , "Old barrier" .)