Work to improve image and appearance that is plain (7)
I believe the answer is:
prairie
'plain' is the definition.
(type of plain)
'work to improve image and appearance that is' is the wordplay.
I cannot quite see how this works, but
'appearance' could be 'air' (both can mean an impression or character) and 'air' is found within the answer.
'that is' could be 'ie' (short for Latin 'id est', 'that is') and 'ie' is found in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for prairie that I've seen before include "Grasslands" , "Broad rolling tract of land in the US" , "Extensive US grassland" , "Continental grassland of N America" , "Open grassland of North America" .)