Head of Beeb managed serial (4)

I believe the answer is:
bran
'serial' is the definition.
Although both the answer and definition are singular nouns, I can't understand how one could define the other.
'head of beeb managed' is the wordplay.
'head of' indicates taking the first letters.
'managed' becomes 'ran' (both can mean organised or was in charge of).
The initial letter of 'beeb' is 'b'.
'b'+'ran'='BRAN'
Can you help me to learn more?
(Other definitions for bran that I've seen before include "Horse-food in barn" , "Milled grain husk" , "Type of edible fibre" , "Coarse meal for horses" , "Food for horses in barn" .)
