State the chief foregone conclusion (5)
I believe the answer is:
maine
'state' is the definition.
(Maine is an example)
'the chief foregone conclusion' is the wordplay.
'the chief' becomes 'main' (I've seen this before).
'conclusion' suggests the final letters.
The final letter of 'foregone' is 'e'.
'main'+'e'='MAINE'
(Other definitions for maine that I've seen before include "state of USA" , "American state, capital Augusta" , "North-east American state" , "The USA's Pine Tree State" , "NE US state" .)