Boxes with credit before a setback (6)
I believe the answer is:
crates
'boxes' is the definition.
(crate is a kind of box)
'credit before a setback' is the wordplay.
'credit' becomes 'cr'.
'before' means one lot of letters go next to another.
'setback' becomes 'tes' (I've seen this in other clues).
'cr'+'a'+'tes'='CRATES'
'with' is the link.
(Other definitions for crates that I've seen before include "Boxes for shipping goods" , "Packing cases" , "Rough wooden boxes" , "Jalopies" .)