Little bit of calm, say (5)
I believe the answer is:
piece
'little bit' is the definition.
'calm say' is the wordplay.
'calm' becomes 'peace' (peaceful situation).
'say' shows a homophone (sound like).
'peace' sounds like 'PIECE'.
'of' acts as a link.
(Other definitions for piece that I've seen before include "wedge a > bit" , "Part - portion" , "man on board" , "A bit of something" , "Musical work; bit" .)