A bit calm, they say (5)
I believe the answer is:
piece
'a bit' is the definition.
(a bit is a small piece)
'calm they say' is the wordplay.
'calm' becomes 'peace' (peaceful situation).
'they say' shows a homophone (sound like).
'peace' sounds like 'PIECE'.
(Other definitions for piece that I've seen before include "King, perhaps" , "king or queen?" , "Castle, perhaps" , "artefact" , "Scrap - musical work" .)