Split finance ultimately invested in London building (6)
I believe the answer is:
shared
'split' is the definition.
(split can mean shared out)
'finance ultimately invested in london building' is the wordplay.
'ultimately' suggests the final letters.
'invested in' means one lot of letters goes inside another.
'london building' becomes 'Shard' (The Shard is a London skyscraper).
The last letter of 'finance' is 'e'.
'e' going into 'shard' is 'SHARED'.
(Other definitions for shared that I've seen before include "Communal" , "Jointly owned" , "Meted out, allotted portions" , "Participated in" , "divided into portions" .)