Pastrami sandwich bread (3)
I believe the answer is:
rye
'pastrami sandwich bread' 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 "(Gypsy) gent; type of bread, whiskey" , "E. Sussex town; cereal" , "Burns's body came through" , "Cereal grain" , "Grass - whiskey" .)