Secluded dwelling Mike included in legacy (9)
I believe the answer is:
hermitage
'secluded dwelling' is the definition.
'mike included in legacy' is the wordplay.
'mike' becomes 'm' (phonetic alphabet: alpha, bravo, charlie etc.).
'included in' indicates putting letters inside.
'legacy' becomes 'heritage' ('heritage' can be a synonym of 'legacy').
'm' placed into 'heritage' is 'HERMITAGE'.
(Other definitions for hermitage that I've seen before include "St Petersburg museum - Rhone wine" , "Secluded retreat" , "Place of retreat" , "Museum housing collection started by Catherine the Great" , "Home of a recluse" .)