Owned a nice building inside Spanish estate (8)
I believe the answer is:
hacienda
'spanish estate' is the definition.
(I've seen this before)
'owned a nice building inside' is the wordplay.
'owned' becomes 'had' ('have' can be a synonym of 'own').
'building' is an anagram indicator.
'inside' means one lot of letters goes inside another.
'nice' is an anagram of 'cien'.
'had'+'a'='hada'
'hada' placed around 'cien' is 'HACIENDA'.
(Other definitions for hacienda that I've seen before include "Spanish house/estate" , "Latin-American estate - I had acne (anag)" , "ranch abroad" , "Estate in Spanish-speaking location" , "Ranch - large estate" .)