Repudiation (6)
I believe the answer is:
denial
'repudiation' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for denial that I've seen before include "Refusal, abnegation" , "Act of asserting that something alleged is not true" , "Refusal to admit painful truths" , "Negation" , "Refusal to acknowledge" .)