Most tractors can be used in vegetable production (6)
I believe the answer is:
carrot
This could be a double definition.
'most tractors can' is the first definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
'used in vegetable production' is the second definition.
The answer and definition can be both acts as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'be' is the link.
Can you help me to learn more?
(Other definitions for carrot that I've seen before include "Vegetable to entice the donkey" , "veg" , "Orangey vegetable" , "Tapering vegetable" , "Incentive (but not the stick)" .)