Annual production — of bakery I’d chat about? (8,4)
I believe the answer is:
Here is my best explanation:
'annual production' is the definition.
(something produced annually)
'bakery i'd chat about?' is the subsidiary indication.
'about?' indicates an anagram.
'bakeryidchat' anagrammed gives 'birthdaycake'.
'of' is the link.
(Other definitions for birthday cake that I've seen before include "Anniversary fare", "Celebratory confection" and "Yearly confection".)