Improves objectives to support half of them (6)
I believe the answer is:
emends
'improves' is the definition.
(emending is a kind of improving)
'objectives to support half of them' is the wordplay.
'objectives' becomes 'ends' (I've seen this before).
'to support' means one lot of letters go next to another.
'half of' means to take half the letters.
'them' cut in half is 'em'.
'ends' after 'em' is 'EMENDS'.
(Other definitions for emends that I've seen before include "'Corrects, puts right (6)'" , "Makes corrections in written material" , "Corrects and improves the text" , "Improves,corrects" , "Makes improvements or corrections" .)