Denial of eating nuts individual left unfinished (8)
I believe the answer is:
negation
'denial' is the definition.
(I know that negation is a type of denial)
'eating nuts individual left unfinished' is the wordplay.
'nuts' is an anagram indicator (nuts can mean crazy).
'individual' becomes 'one' (an individual is one person).
'left unfinished' means to remove the last letter.
'one' with its final letter removed is 'on'.
'eating' is an anagram of 'negati'.
'negati'+'on'='NEGATION'
'of' acts as a link.
(Other definitions for negation that I've seen before include "Disaffirmation" , "people" , "Contradiction" , "Refutation by Antigone" , "Making denial" .)