Some present I mentioned giving opinion (9)
I believe the answer is:
sentiment
'opinion' is the definition.
('sentiment' can be a synonym of 'opinion')
'some present i mentioned' is the wordplay.
'some' says the answer is hidden in the clue (some of the parts of the word are used).
'SENTIMENT' is hidden within 'present i mentioned'.
'giving' is the link.
(Other definitions for sentiment that I've seen before include "Tender feeling" , "Emotional feeling" , "Test men in, say, emotion" , "Slush" , "View, opinion, feeling" .)