Plain couple that is accepting resistance (7)
I believe the answer is:
prairie
'plain' is the definition.
(type of plain)
'couple that is accepting resistance' is the wordplay.
'couple' becomes 'pair' (synonyms).
'that is' becomes 'ie' (short for Latin 'id est', 'that is').
'accepting' means one lot of letters goes inside another (inserted letters are accepted).
'resistance' becomes 'r' (electronics abbreviation).
'pair'+'ie'='pairie'
'pairie' going around 'r' is 'PRAIRIE'.
(Other definitions for prairie that I've seen before include "Large open area of grassland in the US" , "Treeless grassy plain, in the old West perhaps" , "this oyster produces an egg" , "Wide grassy plain" , "North American grassland" .)