Home help upset country (5)
I believe the answer is:
plain
'country' is the definition.
(I have seen 'open country' mean 'plain' so perhaps 'country' could also mean 'plain')
'home help upset' is the wordplay.
I cannot really see how this works, but
'home' could be 'in' ('he's home' can mean 'he's in') and 'in' is present in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for plain that I've seen before include "Undecorated; flat area" , "Clear - open - grassland" , "Unembellished" , "Unadorned on flat area" , "Ordinary; area of land" .)