Rough sea point after calm (4)
I believe the answer is:
ease
'calm' is the definition.
(I've seen this before)
'rough sea point after' is the wordplay.
'rough' indicates an anagram.
'point' becomes 'E' (E is an example).
'after' says to put letters next to each other.
'sea' with letters rearranged gives 'eas'.
'eas'+'e'='EASE'
(Other definitions for ease that I've seen before include "Alleviate" , "nonchalance!" , "Assuage" , "Make less severe, comfort" , "Relieve or slacken" .)