Question imbibing English dairy product (4)
I believe the answer is:
whey
'dairy product' is the definition.
(whey is a kind of dairy product)
'question imbibing english' is the wordplay.
'question' becomes 'why' (I've seen this before).
'imbibing' means one lot of letters goes inside another.
'english' becomes 'e' (abbreviation).
'why' going around 'e' is 'WHEY'.
(Other definitions for whey that I've seen before include "11 Across residue" , "Product of clotting milk" , "Watery part of milk after curd separation" , "Watery stuff from clotted milk" , "Watery dairy product" .)