Silent about speaker, I agreed postponement (10)
I believe the answer is:
moratorium
'agreed postponement' is the definition.
(I've seen this before)
'silent about speaker i' is the wordplay.
'silent' becomes 'mum' (synonyms).
'about' means one lot of letters goes inside another.
'speaker' becomes 'orator' (orator is a kind of speaker).
'orator'+'i'='oratori'
'mum' placed around 'oratori' is 'MORATORIUM'.
(Other definitions for moratorium that I've seen before include "Temporary halt in activity" , "Legal delay" , "Prohibition" , "agreed postponement" , "Agreed pause in activity" .)