What’s left outside front of mean retreat (9)
I believe the answer is:
hermitage
'retreat' is the definition.
(a hermitage may be a religious retreat)
'what's left outside front of' is the wordplay.
'what's left' becomes 'heritage' (what's left by previous generations).
'outside' indicates putting letters inside.
'front of' becomes 'm' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'heritage' placed around 'm' is 'HERMITAGE'.
'mean' is the link.
(Other definitions for hermitage that I've seen before include "Home of a recluse" , "Place of retreat" , "Secluded retreat" , "art museum" , "accommodation for one" .)