More than one saw a Degas vandalised (6)
I believe the answer is:
adages
'more than one saw' is the definition.
('adage' can be a synonym of 'saw')
'a degas vandalised' is the wordplay.
'vandalised' indicates anagramming the letters.
'degas' is an anagram of 'dages'.
'a'+'dages'='ADAGES'
(Other definitions for adages that I've seen before include "Much-used wise sayings" , "Old sayings, proverbs" , "Old familiar sayings" , "'Proverbs, saws (6)'" , "Proverbs or maxims" .)