Quarrels about Enids shockingly noisy behaviour (9)
I believe the answer is:
rowdiness
'noisy behaviour' is the definition.
(I've seen this before)
'quarrels about enids shockingly' is the wordplay.
'quarrels' becomes 'rows' ('row' can be a synonym of 'quarrel').
'about' means one lot of letters goes inside another.
'shockingly' indicates anagramming the letters.
'enids' is an anagram of 'dines'.
'rows' going around 'dines' is 'ROWDINESS'.
(Other definitions for rowdiness that I've seen before include "noisy behaviour" , "Wordiness leading to boisterous behaviour" , "Disorderly behaviour" , "Noise, disorder" , "bad behaviour" .)