Convict in stately home looting (7)
I believe the answer is:
pillage
'looting' is the definition.
(I know that pillage is a type of looting)
'convict in stately home' is the wordplay.
'convict' becomes 'lag' (I've seen this before).
'in' indicates putting letters inside.
'stately home' becomes 'pile' (I've seen this in other clues).
'lag' placed into 'pile' is 'PILLAGE'.
(Other definitions for pillage that I've seen before include "Rob with violence" , "Sacking" , "Plunder, sack" , "Violent stealing" , "Loot" .)