Article about suburbs of Tokyo on top of that (7)
I believe the answer is:
thereto
'on top of that' is the definition.
I can't judge whether this definition defines the answer.
'article about suburbs of tokyo' is the wordplay.
'article' becomes 'the' (the definite article in English).
'about' becomes 're' ('re' means regarding or about).
'suburbs of' suggests removing the centre (suburbs are the edges of a city).
'tokyo' with its middle taken out is 'to'.
'the'+'re'+'to'='THERETO'
Can you help me to learn more?
(Other definitions for thereto that I've seen before include "To that place" , "Up to that point" , "In addition" .)