Section is said to be calm (5)
I believe the answer is:
piece
'section' is the definition.
(I've seen this in another clue)
'said to be calm' is the wordplay.
'said to be' indicates a 'sounds like' (homophone) clue.
'calm' becomes 'peace' (peaceful situation).
'peace' is a homophone of 'PIECE'.
'is' is the link.
(Other definitions for piece that I've seen before include "Bit; item" , "Portion, coin, item" , "Morsel" , "E.g. bishop" , "Chessman; portion" .)