Constant congestion unsettled the authorities (11)
I believe the answer is:
cognoscenti
'the authorities' is the definition.
Although both the answer and definition are singular nouns, I don't understand how one could define the other.
'constant congestion unsettled' is the wordplay.
'constant' becomes 'c' (common symbol in maths for an unknown constant).
'unsettled' is an anagram indicator.
'congestion' is an anagram of 'ognoscenti'.
'c'+'ognoscenti'='COGNOSCENTI'
Can you help me to learn more?
(Other definitions for cognoscenti that I've seen before include "Well-informed people" , "Subject experts" , "connoisseurs" , "Those well-informed on a particular subject" , "Knowledgeable types" .)