Virtues shown by monarch in swirling mist (6)
I believe the answer is:
merits
'virtues' is the definition.
('merit' can be a synonym of 'virtue')
'monarch in swirling mist' is the wordplay.
'monarch' becomes 'er' (abbreviation for Elizabeth Regina).
'in' indicates putting letters inside.
'swirling' indicates an anagram.
'mist' anagrammed gives 'mits'.
'er' going within 'mits' is 'MERITS'.
'shown by' is the link.
(Other definitions for merits that I've seen before include "Deserves to be praised" , "Deserves or warrants" , "Virtues of timers" , "Deserves, is worthy of" , "Legally right or wrong" .)