The law destroyed riches (6)
I believe the answer is:
wealth
'riches' is the definition.
(synonyms)
'the law destroyed' is the wordplay.
'destroyed' indicates anagramming the letters.
'the'+'law'='thelaw'
'thelaw' anagrammed gives 'WEALTH'.
(Other definitions for wealth that I've seen before include "Possessions and resources" , "capital" , "Mammon" , "An abundance of valuable possessions or money" , "State of luxury" .)