There are stacks of it out of town (3)
I believe the answer is:
hay
'town' is the definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for hay that I've seen before include "Meadow crop" , "Cut and dried grass" , "Forage" , "Dried grass as fodder" , "Dried mown grass" .)