Blonde seen after a month in part of London (7)
I believe the answer is:
mayfair
'part of london' is the definition.
(I've seen this before)
'blonde seen after a month' is the wordplay.
'blonde' becomes 'fair' (similar in meaning).
'seen after' says to put letters next to each other.
'a month' becomes 'May' (May is an example).
'fair' put after 'may' is 'MAYFAIR'.
'in' is the link.
(Other definitions for mayfair that I've seen before include "capital area" , "Prosperous part of our capital" , "address in fashionable area" , "Go immediately after this" , "expensive area of London" .)