Dialogue (8)
(Other definitions for speaking that I've seen before include "a way of passing the word" , "oratory" , "conveying meaning" , "Saying something" , "Talking" .)
'dialogue' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for colloquy that I've seen before include "mutual discourse" , "Formal conversation" , "Dialogue" .)