Retrograde prison part of extremely lousy inheritance (6)
I believe the answer is:
legacy
'inheritance' is the definition.
(synonyms)
'retrograde prison part of extremely lousy' is the wordplay.
'retrograde' is a reversal indicator.
'prison' becomes 'cage' (I've seen this before).
'part of' indicates putting letters inside (part of the inside).
'extremely' suggests removing the centre.
'lousy' with its centre taken out is 'ly'.
'cage' in reverse letter order is 'egac'.
'egac' placed within 'ly' is 'LEGACY'.
(Other definitions for legacy that I've seen before include "Bombay since 1995" , "One inherited" , "Inheritance" , "What is left to one in will" , "Something bequeathed in will" .)