Big retailer's rule for salad item (8)
I believe the answer is:
coleslaw
'item' is the definition.
Although both the answer and definition are singular nouns, I can't see how one could define the other.
'big retailer's rule for salad' is the wordplay.
'big retailer's rule' becomes 'cole' (I can't explain this - if you can you should believe this answer much more).
'for' is a charade indicator (letters next to each other).
'salad' becomes 'slaw' (slaw is a kind of salad).
'cole'+'slaw'='COLESLAW'
Can you help me to learn more?
(Other definitions for coleslaw that I've seen before include "Indeed" , "Salad dish of shredded cabbage, etc" , "Salad of mainly cabbage" , "Salad of shredded vegetables" , "healthy food" .)