For transport, one may get the sorrel out (7)
I believe the answer is:
lorries
'for transport one' is the definition.
I can't judge whether this defines the answer.
'may get the sorrel out' is the wordplay.
'may' becomes 'i' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'get' is an insertion indicator.
'out' indicates an anagram (out can mean wrong or inaccurate).
'sorrel' with letters rearranged gives 'lorres'.
'i' inserted within 'lorres' is 'LORRIES'.
Can you help me to learn more?
(Other definitions for lorries that I've seen before include "Vehicles for transporting goods" , "Large motor vehicles for carrying heavy goods" , "Large transport vehicles" , "Truck with no sides" , "forms of transport" .)