Plain dress I repair (7)
I believe the answer is:
prairie
'plain' is the definition.
(type of plain)
'dress i repair' is the wordplay.
'dress' is an anagram indicator (dress or prepare the letters).
'i'+'repair'='irepair'
'irepair' with letters rearranged gives 'PRAIRIE'.
(Other definitions for prairie that I've seen before include "Wide grassy plain" , "Grasslands" , "Barren plain" , "Broad rolling tract of land in the US" , "-- Dog; -- oyster" .)