Menu finale is in the oven (6)
I believe the answer is:
agenda
'menu' is the definition.
(I've seen this before)
'finale is in the oven' is the wordplay.
'finale' becomes 'end' (the end of a story or show).
'is in the' means one lot of letters goes inside another.
'oven' becomes 'aga' (type of large oven).
'end' inserted within 'aga' is 'AGENDA'.
(Other definitions for agenda that I've seen before include "Schedule - things to be done" , "List of things to be done or discussed" , "List of items to be dealt with" , "Items of business for committee meeting" , "Topics for a meeting" .)