Aim to finish (3)
I believe the answer is:
end
I believe this clue is a double definition.
'aim' is the first definition.
(both can mean a goal or purpose)
'finish' is the second definition.
(I know that finish can be written as end)
'to' is the link.
(Other definitions for end that I've seen before include "Conclusion or goal" , "Discontinue" , "ambition" , "American footballer" , "SECOND PART OF 24" .)