The plainsman's home? (4)
I believe the answer is:
flat
This could be a double definition.
'the plainsman's' is the first definition.
Although both the answer and definition are singular nouns, I can't see how they can define each other.
'home?' is the second definition.
(flat is a type of home or residence)
Can you help me to learn more?
(Other definitions for flat that I've seen before include "razed to the ground, having had blow-out" , "Unnatural - uninteresting - apartment" , "Apartment - on the level" , "Even - somewhere to live" , "Digs perhaps" .)