Lout with basin ruined washing ceremony (9)
I believe the answer is:
ablutions
'washing ceremony' is the definition.
(ablution can humorously mean an act of washing)
'lout with basin ruined' is the wordplay.
'with' is a charade indicator (letters next to each other).
'ruined' indicates anagramming the letters.
'lout' put after 'basin' is 'basinlout'.
'basinlout' is an anagram of 'ABLUTIONS'.
(Other definitions for ablutions that I've seen before include "The act of washing" , "wash and brush-up" .)