Price reduction (8)
'price reduction' is the definition.
(I know that price reduction can be written as discount)
This is all the clue.
(Other definitions for discount that I've seen before include "Ignore - price reduction" , "Reduction in cost" , "Disregard; cost cut" , "Do tunics attract reduction in price?" , "Deduction granted on payment" .)
(Other definitions for markdown that I've seen before include "Lower prices for 21" , "Reduction in price" , "Reduce in price" .)