New mode of building (4)
I believe the answer is:
dome
'building' is the definition.
(I've seen this before)
'new mode' is the wordplay.
'new' indicates an anagram.
'mode' with letters rearranged gives 'DOME'.
'of' is the link.
(Other definitions for dome that I've seen before include "Rounded vault of a roof" , "A stately building" , "Rounded roof with circular base" , "millennium feature" , "Curved roof" .)