Turn bit of brie in rasher into sandwich (6)
I believe the answer is:
sarnie
'sandwich' is the definition.
(I've seen this before)
'turn bit of brie in rasher' is the wordplay.
'turn' is a reversal indicator.
'bit of' says the answer is hidden in the clue.
'einras' can be found hidden inside 'brie in rasher'.
'einras' backwards is 'SARNIE'.
'into' acts as a link.
(Other definitions for sarnie that I've seen before include "Sandwich (informal)" , "Popular bread-based snack (colloq)" , "no classy fare" , "Two slices of bread with a filling" , "Bread and filling snack (informal)" .)