Rubbish vehicle reversing — that's driven across fields (7)
I believe the answer is:
tractor
'that's driven across fields' is the definition.
I can't tell whether this defines the answer.
'rubbish vehicle reversing' is the wordplay.
'rubbish' becomes 'rot' (both can mean nonsense).
'vehicle' becomes 'cart' (cart is a kind of vehicle).
'reversing' says the letters should be written in reverse.
'rot'+'cart'='rotcart'
'rotcart' back-to-front is 'TRACTOR'.
Can you help me to learn more?
(Other definitions for tractor that I've seen before include "Farm machine used for pulling" , "Agricultural vehicle" , "Vehicle for pulling farm machinery" , "Agricultural machine" , "Type of truck with a a cab but no body" .)