French art rogue returned property (7)
I believe the answer is:
escheat
'returned property' is the definition.
(property returned to the state)
'french art rogue' is the wordplay.
'french art' becomes 'es' ('is' in French - 'art' can mean 'is' eg 'thou art').
'rogue' becomes 'cheat' (I've seen this before).
'es'+'cheat'='ESCHEAT'
(Other definitions for escheat that I've seen before include "Property returned" , "Confiscate" , "property taken by Crown" , "reversion of property" , "forfeited property" .)