Gathered idiot and Eastern doctor went first (9)
I believe the answer is:
assembled
'gathered' is the definition.
('assemble' can be a synonym of 'gather')
'idiot and eastern doctor went first' is the wordplay.
'idiot' becomes 'ass' (I've seen this in another clue).
'and' is a charade indicator (letters next to each other).
'eastern' becomes 'e'.
'doctor' becomes 'MB' (Bachelor of Medicine, Medicinae Baccalaureus).
'went first' becomes 'led' (I've seen this in another clue).
'ass'+'e'+'mb'+'led'='ASSEMBLED'
(Other definitions for assembled that I've seen before include "Convened came together" , "Constructed" , "Came together or put together" , "Congregated, gathered" , "Got together" .)