Great fun bottling our dairy product (4,5)
I believe the answer is:
sour cream
'dairy product' is the definition.
(sour cream is a kind of dairy product)
'great fun bottling our' is the wordplay.
'great fun' becomes 'scream' (I can't explain this - if you can you should believe this answer much more).
'bottling' indicates putting letters inside (bottling is a kind of containing).
'scream' placed around 'our' is 'SOUR CREAM'.
Can you help me to learn more?
(Other definitions for sour cream that I've seen before include "dip" , "cooking ingredient" , "Fermented dairy product" , "Rich savoury food" , "salad dressing" .)