Final word is not quite correct (4)
I believe the answer is:
amen
'final word' is the definition.
(I've seen this before)
'not quite correct' is the wordplay.
'not quite' means to remove the last letter.
'correct' becomes 'amend' (amending is a kind of correcting).
'amend' with its final letter taken away is 'AMEN'.
'is' is the link.
(Other definitions for amen that I've seen before include "Conclusion of prayer" , "Final word in prayer" , "Churchgoer's assent?" , "as agreed!" , "Word of approval" .)