In part of kitchen, superior variety of wheat (5)
I believe the answer is:
durum
'variety of wheat' is the definition.
(I've seen this before)
'in part of kitchen superior' is the wordplay.
'in' means one lot of letters goes inside another.
'part of kitchen' becomes 'drum' (the kitchen is an orchestra's percussion section).
'superior' becomes 'U' (U can mean upper-class, as in U and non-U speech).
'drum' placed around 'u' is 'DURUM'.
(Other definitions for durum that I've seen before include "Kind of hard wheat" , "Wheat for pasta flour" , "Wheat variety" , "Type of flour used for pasta" , "It makes pasta" .)