Constituent sounded out truce (5)
I believe the answer is:
piece
'constituent' is the definition.
(I've seen this before)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for piece that I've seen before include "newspaper article" , "Bit; item" , "Castle, perhaps" , "Portion, coin, item" , "Portion, bit" .)