Price cut for lettuce (3)
I believe the answer is:
cos
'lettuce' is the definition.
(cos lettuce is a kind of lettuce)
'price cut' is the wordplay.
'price' becomes 'cost' ('cost' can be a synonym of 'price').
'cut' means to remove the last letter.
'cost' with its last letter removed is 'COS'.
'for' is the link.
(Other definitions for cos that I've seen before include "Chief of Staff" , "Function briefly" , "Casual as" , "something of a salad" , "Salad plant" .)