An object to destroy (3)
I believe the answer is:
end
This could be a double definition.
'an object' is the first definition.
The answer and definition can be both related to thinking as well as being singular nouns.
Maybe you can see a link between them that I don't see?
'destroy' is the second definition.
(I've seen this in another clue)
'to' acts as a link.
Can you help me to learn more?
(Other definitions for end that I've seen before include "'Finish, cease (3)'" , "ambition" , "result" , "Conclusion, finish" , "Unyielding" .)