What the truce will achieve, you say, for a bit (5)
I believe the answer is:
piece
'for a bit' is the definition.
(a bit is a small piece)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for piece that I've seen before include "Musical work; bit" , "Section; firearm" , "Queen on board, perhaps" , "Single article" , "constituent" .)