Pumpernickel alternative (3)
I believe the answer is:
rye
'pumpernickel alternative' 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 "Whiskey (US)" , "A Cinque Port; a grain" , "Hard liquor" , "East Sussex resort" , "J D Salinger novel 'The Catcher in the ...'" .)