Hike miles conveyed by horse-drawn carriage (5)
I believe the answer is:
tramp
'hike' is the definition.
(I've seen this before)
'miles conveyed by horse-drawn carriage' is the wordplay.
'miles' becomes 'm' (common abbreviation).
'conveyed by' means one lot of letters goes inside another.
'horse drawn carriage' becomes 'trap'.
'm' placed into 'trap' is 'TRAMP'.
(Other definitions for tramp that I've seen before include "I usually walk" , "Hike" , "Walk heavily and firmly" , "Walk with heavy steps like hobo" , "Heavily plod around" .)