Lettuce obtained at reduced cost (3)
I believe the answer is:
cos
'lettuce' is the definition.
(cos is a kind of lettuce)
'reduced cost' is the wordplay.
'reduced' means to remove the last letter.
'cost' with its last letter taken away is 'COS'.
'obtained at' is the link.
This may not be right. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for cos that I've seen before include "Casual as" , "holiday destination" , "Greek island (alternative spelling): Trig abbrev!" , "in the Dodecanese?" , "A long-leaved lettuce" .)