Summit meeting’s principle bores expert (4)
I believe the answer is:
acme
'summit' is the definition.
(synonyms)
'meeting's principle bores expert' is the wordplay.
'meeting's principle' becomes 'm' (I am not sure about this - if you are sure you should believe this answer much more).
'bores' is an insertion indicator (to bore something can mean to drill into it).
'expert' becomes 'ace' (ace can informally mean very good).
'm' placed into 'ace' is 'ACME'.
Can you help me to learn more?
(Other definitions for acme that I've seen before include "Top; peak" , "Highest stage of development" , "High point of excellence" , "Highest point (of something)" , "'Highest point, apex (4)'" .)