Plain dish containing last but one portion of savoury spread (7)
I believe the answer is:
prairie
'plain' is the definition.
(type of plain)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for prairie that I've seen before include "Tract of (US) grassland" , "North American grassland" , "Large open area of grassland in the US" , "Extensive US grassland" , "Cowboy song: ` `Bury me not on the lone .......' '" .)