Seen working to get queen calm (6)
I believe the answer is:
serene
'calm' is the definition.
('serene' can be a synonym of 'calm')
'seen working to get queen' is the wordplay.
'working' is an anagram indicator.
'to get' means one lot of letters goes inside another.
'queen' becomes 'er' (abbreviation for Elizabeth Regina).
'seen' with letters rearranged gives 'sene'.
'sene' enclosing 'er' is 'SERENE'.
(Other definitions for serene that I've seen before include "Tranquil, perfectly calm" , "Totally unagitated" , "Calm and unclouded" , "Calm and unruffled, like a princely title." , "Not agitated" .)