Quieten doe unsettled in swirling wind (3,4)
I believe the answer is:
die down
'quieten' is the definition.
(I've seen this before)
'doe unsettled in swirling wind' is the wordplay.
'unsettled' indicates an anagram.
'in' means one lot of letters goes inside another.
'swirling' indicates anagramming the letters.
'doe' is an anagram of 'edo'.
'wind' anagrammed gives 'diwn'.
'edo' going into 'diwn' is 'DIE DOWN'.
(Other definitions for die down that I've seen before include "For ease" , "get quiet" , "become quieter" , "Become progressively weaker" , "Become less loud/strong" .)