Beef fillet to sell more cheaply (8)
I believe the answer is:
undercut
I believe this is a double definition.
'beef fillet' is the first definition.
(I know that beef fillet can be written as undercut)
'sell more cheaply' is the second definition.
(I've seen this in another clue)
'to' acts as a link.
(Other definitions for undercut that I've seen before include "Offer goods at a lower price to beat a competitor" , "strike" , "As a business person try to outmanoeuvre" , "produce relief" , "Slice below or lower prices" .)