Question about English dairy product? (4)
I believe the answer is:
whey
'dairy product' is the definition.
(I know that whey is a type of dairy product)
'question about english' is the wordplay.
'question' becomes 'why' (why is a question word).
'about' is an insertion indicator.
'english' becomes 'E' (abbreviation).
'why' placed around 'e' is 'WHEY'.
(Other definitions for whey that I've seen before include "Residual liquid from clotted milk" , "Watery part of milk after curd separation" , "Watery content of milk" , "Watery residue of milk" , "Watery dairy product" .)