As a dairy product, you can pack it up (6)
I believe the answer is:
cheese
'as' is the definition.
Although both the answer and definition are singular nouns, I cannot see how they can define each other.
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for cheese that I've seen before include "Product of milk curds" , "Edam or cheddar, say" , "Edam, Brie, Cheddar..." , "Lancashire, perhaps" , "Gloucester or Gubbeen, say" .)