Royal Botanic Gardens in London (3)
I believe the answer is:
kew
'royal botanic gardens in london' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for kew that I've seen before include "SW London Gardens" , "Garden location" , "Location of the Royal Botanic Gardens in London" , "part of London" , "Botanic gardens site" .)