Rustic wall painting showing river for miles (5)
I believe the answer is:
rural
'rustic' is the definition.
(similar in meaning)
'wall painting showing river for miles' is the wordplay.
I cannot quite see how this works, but
'river' could be 'ural' (I've seen this before) and 'ural' is located in the answer.
A single letter 'r' remains which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for rural that I've seen before include "Cobbett saw on his rides?" , "Countrified" , "Old country fellow" , "covering the country" , "Sort of dean" .)