Debatable beastly utterance by an East Ender (4)
I believe the answer is:
moot
'debatable' is the definition.
(synonyms)
'beastly utterance by an east ender' is the wordplay.
'beastly utterance' becomes 'moo' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'by' is a charade indicator (letters next to each other).
'ender' says to take the final letters (I've seen 'ending' mean this).
The last letter of 'east' is 't'.
'moo'+'t'='MOOT'
Can you help me to learn more?
(Other definitions for moot that I've seen before include "raise for discussion" , "Undecided as a debatable point may be" , "Propose for discussion" , "Open to question" , "Controversial" .)