Disown erudite ape's endless rambling (9)
I believe the answer is:
repudiate
'disown' is the definition.
(I know that disown can be written as repudiate)
'erudite ape's endless rambling' is the wordplay.
'endless' means to remove the last letter.
'rambling' is an anagram indicator.
'erudite'+'ape'='eruditeape'
'eruditeape' with its last letter taken away is 'eruditeap'.
'eruditeap' with letters rearranged gives 'REPUDIATE'.
(Other definitions for repudiate that I've seen before include "Make a disclaimer" , "Give denial" , "Renounce, disown" , "Refuse to be associated with" , "Denounce" .)