Stories about ordinary runs with cargo essentially in heavy vehicles (7)
I believe the answer is:
lorries
'vehicles' is the definition.
(lorry is a kind of vehicle)
'stories about ordinary runs' is the wordplay.
'stories' becomes 'lies' (to tell stories can mean to lie).
'about' means one lot of letters goes inside another.
'ordinary' becomes 'O' (abbreviation e.g. O-Levels).
'runs' becomes 'rr' (r is abbreviation for run in cricket, twice).
'o'+'rr'='orr'
'lies' enclosing 'orr' is 'LORRIES'.
'with cargo essentially in heavy' is the link.
This may not be right. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for lorries that I've seen before include "HGVs" , "Cargo vehicles" , "Truck with no sides" , "Vehicles for transporting goods" , "Large transport vehicles" .)