Reduced price for salad ingredient (3)
I believe the answer is:
cos
'salad ingredient' is the definition.
(type of lettuce)
'reduced price' is the wordplay.
'reduced' means to remove the last letter.
'price' becomes 'cost' (synonyms).
'cost' with its final letter taken away is 'COS'.
'for' is the link.
(Other definitions for cos that I've seen before include "leaves > function" , "Casual as" , "healthy food" , "Island in Mediterranean" , "naturally having longer leaves than most" .)