Labor leader snuck into foreign embassy meeting (8)
I believe the answer is:
assembly
'meeting' is the definition.
(I've seen this before)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for assembly that I've seen before include "Gathering, congregation" , "start of day at school" , "School morning gathering" , "Religious gathering" , "Gathering of people or fitting of parts together" .)