Bread for a Reuben (3)
I believe the answer is:
'bread for a reuben' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for rye that I've seen before include "Bitterly regret" , "East Sussex resort" , "Grain - whiskey - port" , "Hardy cereal crop" , "Type of grass" .)