Babble about endless rule governing part of sentence (9)
I believe the answer is:
predicate
'part of sentence' is the definition.
(I've seen this before)
'babble about endless rule governing' is the wordplay.
I cannot quite see how this works, but
'about' could be 're' (regarding) and 're' is located in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for predicate that I've seen before include "Describes part of a sentence" , "Grammatically, the statement made about a subject" , "Found" , "base" , "Word or words that function as a verb" .)