British controlled grain by-products (4)
I believe the answer is:
bran
'grain by-products' is the definition.
'bran' can be an answer for 'grain' (thesaurus). I am not sure about the 'by-products' bit.
'british controlled' is the wordplay.
'british' becomes 'b' (abbreviation e.g. in 'BBC').
'controlled' becomes 'ran' (I've seen this in other clues).
'b'+'ran'='BRAN'
Can you help me to learn more?
(Other definitions for bran that I've seen before include "Milled grain husk" , "Husks of grain sifted from the flour" , "Food for horses in barn" , "Husks of cereal seeds sifted from flour" , "Separated grain husks" .)