Old royal part of London (8)
I believe the answer is:
victoria
This clue is a double definition.
'old royal' is the first definition.
(Queen Victoria)
'part of london' is the second definition.
(Victoria is an area of London)
(Other definitions for victoria that I've seen before include "Tree; part of hand" , "Monarch" , "falls in > London station" , "Girl" , "Mrs Beckham" .)