Leaders from Europe, lo and behold, make a speech complicated (9)
I believe the answer is:
elaborate
'complicated' is the definition.
(I've seen this in another clue)
'leaders from europe lo and behold make a speech' is the wordplay.
'leaders from' indicates taking the first letters.
'make a speech' becomes 'orate' (oratory is public speaking).
The first letters of 'europe lo and behold' is 'elab'.
'elab'+'orate'='ELABORATE'
(Other definitions for elaborate that I've seen before include "Extravagant" , "With many parts or details, maybe a pattern" , "Highly detailed" , "Fussy" , "Explain details" .)