Money invested in London? (7)
I believe the answer is:
capital
I believe this is a double definition.
'money invested' is the first definition.
(I've seen this before)
'london?' is the second definition.
(london is a kind of capital)
'in' is the link.
(Other definitions for capital that I've seen before include "Upper case city" , "Hamilton, perhaps" , "Finances" , "Means" , "source of profit" .)