Foreign Office leading odd discussion meeting (5)
I believe the answer is:
forum
'discussion meeting' is the definition.
(I've seen this before)
'foreign office leading odd' is the wordplay.
'foreign office' becomes 'fo'.
'leading' is a charade indicator (letters next to each other).
'odd' becomes 'rum' (I've seen this before).
'fo'+'rum'='FORUM'
(Other definitions for forum that I've seen before include "Place to discuss ideas" , "place for debate" , "old square" , "discussion group" , "Internet message board" .)