What’s coming on Monday? Not a whisky (3)
I believe the answer is:
rye
'whisky' is the definition.
(rye whisky is a kind of whisky)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for rye that I've seen before include "A Cinque Port; a grain" , "Cereal grass - Sussex Cinque Port" , "Bitterly regret" , "(Gypsy) gent; type of bread, whiskey" , "21 [GRASS]" .)