Arch collapsed round new hacienda (5)
I believe the answer is:
ranch
'hacienda' is the definition.
(I've seen this before)
'arch collapsed round new' is the wordplay.
'collapsed' is an anagram indicator.
'round' means one lot of letters goes inside another.
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'arch' anagrammed gives 'rach'.
'rach' going around 'n' is 'RANCH'.
(Other definitions for ranch that I've seen before include "Large American farm" , "Agricultural business" , "stock holding?" , "North American stock farm" , "where stock is held" .)