Closed discussion? Not quite complete (5)
I believe the answer is:
total
'complete' is the definition.
('total' can be a synonym of 'complete')
'closed discussion? not quite' is the wordplay.
'closed' becomes 'to' (I can't explain this - if you can you should believe this answer much more).
'discussion?' becomes 'talk' (talk is a kind of discussion).
'not quite' means to remove the last letter.
'talk' with its last letter taken away is 'tal'.
'to'+'tal'='TOTAL'
(Other definitions for total that I've seen before include "Aggregate amount" , "Comprehensive" , "Including all" , "Full, entire amount" , "wreck" .)