Fool European maiden by holding large meeting (8)
I believe the answer is:
assembly
'meeting' is the definition.
(I've seen this in another clue)
'fool european maiden by holding large' is the wordplay.
'fool' becomes 'ass' (both can mean a stupid person).
'european' becomes 'e' (abbreviation e.g. EU).
'maiden' becomes 'm' (cricket abbreviation).
'holding' is an insertion indicator.
'large' becomes 'L' (eg in clothes sizes).
'by' enclosing 'l' is 'bly'.
'ass'+'e'+'m'+'bly'='ASSEMBLY'
(Other definitions for assembly that I've seen before include "Gathering, congregation" , "A gathering for formal meeting" , "synod" , "School morning gathering" , "Body of people that meets" .)