Enough to prevent parting without meeting (6)
I believe the answer is:
'meeting' is the definition.
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for quorum that I've seen before include "Number sufficient for business" , "Min. no. for a meeting" , "Minimum number needed to take decisions" , "Number validating a meeting" , "Minimal number required to conduct business" .)