Plain menu with posh ingredients (8)
I believe the answer is:
homespun
'plain' is the definition.
(thesaurus)
'menu with posh ingredients' is the wordplay.
'with' says to put letters next to each other.
'ingredients' is an anagram indicator.
'menu' after 'posh' is 'poshmenu'.
'poshmenu' with letters rearranged gives 'HOMESPUN'.
(Other definitions for homespun that I've seen before include "Unsophisticated -- posh menu (anag)" , "Simple, unsophisticated" , "Folksy - open mush (anag)" , "Rustic" , "Unsophisticated - not made in mill" .)