A corny group in the country field (5)
I believe the answer is:
sheaf
This clue could be a double definition.
'a corny group' is the first definition.
Although both the answer and definition are singular nouns, I don't see how they can define each other.
'country field' is the second definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
'in the' is the link.
Can you help me to learn more?
(Other definitions for sheaf that I've seen before include "Bundle of wheat" , "Collection of papers" , "Stack, bundle" , "A bundle, of corn stalks or papers" , "Tied bundle (of corn)" .)