Not worth debating (4)
I believe the answer is:
moot
'not worth debating' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for moot that I've seen before include "Open to argument or debate" , "Propose for discussion" , "Such a point is disputable" , "Subject to dispute" , "Anglo-Saxon assembly; subject to debate" .)