Merry session around east end of London's curiosity (8)
I believe the answer is:
'curiosity' is the definition.
(nosiness is a kind of curiosity)
'merry session around east end of london's' is the wordplay.
I cannot quite understand how this works, but
an anagram of 'session' is 'osiness' which is located in the answer.
A single letter 'n' remains which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for nosiness that I've seen before include "Curiosity of nasal kind", "Inquisitiveness", "Inquisitive quality", "Tendency to pry", "Inquisitive characteristic".)