Financial institution ruins new queen (7)
I believe the answer is:
insurer
'financial institution' is the definition.
(I know that insurer is a type of nondepository financial institution)
'ruins new queen' is the wordplay.
'new' indicates anagramming the letters.
'queen' becomes 'ER' (abbreviation for Elizabeth Regina).
'ruins' is an anagram of 'insur'.
'insur'+'er'='INSURER'
(Other definitions for insurer that I've seen before include "One paying out in event of damage" , "Provider of a security policy" , "One providing cover" , "One offering cover" , "Provider of cover" .)