Terrible avarice brought about new disagreement (8)
I believe the answer is:
variance
'disagreement' is the definition.
(I know that variance is a type of discord)
'terrible avarice brought about new' is the wordplay.
'terrible' indicates an anagram.
'brought about' indicates putting letters inside.
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'avarice' with letters rearranged gives 'variace'.
'variace' placed around 'n' is 'VARIANCE'.
(Other definitions for variance that I've seen before include "Change" , "Difference, discrepancy" , "disagreement" , "Discrepancy, divergence" , "Not the main attraction" .)