Clergymen in the army wanting tea in open country (6)
I believe the answer is:
plains
'clergymen' is the definition.
Although both the answer and definition are plural nouns, I can't see how they can define each other.
'in the army wanting tea in open country' is the wordplay.
I cannot really see how this works, but
'in' is within the answer.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for plains that I've seen before include "Spinal (anag.)" , "Flat tracts of land" , "Extensive tracts of level open land" , "Large areas of level country" , "Large tracts of level open land" .)