Bundle for a mansion (4)
I believe the answer is:
pile
This clue is a double definition.
'bundle' is the first definition.
(thesaurus)
'a mansion' is the second definition.
(I've seen this in other clues)
'for' acts as a link.
(Other definitions for pile that I've seen before include "supporting column" , "lot of money" , "large building" , "Large number" , "large amount of money" .)