Producer's factory in the river (2,5)
I believe the answer is:
de mille
'producer's' is the definition.
Both the answer and definition are singular nouns.
Maybe they are linked in a way I don't understand?
'factory in the river' is the wordplay.
'factory' becomes 'mill' (mill is a type of factory).
'in the' indicates putting letters inside.
'river' becomes 'dee' (River Dee).
'mill' put inside 'dee' is 'DE MILLE'.
Can you help me to learn more?
(Other definitions for de mille that I've seen before include "Showman" , "Cecil B - - (film pioneer)" , "Cecil B. -- --, US film producer/director" , "Cecil B. -, producer" , "Cecil B - - - - (films)" .)