Gracious old people confirming who's boss (10)
I believe the answer is:
coronation
'confirming who's boss' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
'gracious old people' is the wordplay.
'gracious' becomes 'cor' (both are exclamations of surprise).
'old' becomes 'o' (abbreviation as in OT - Old Testament).
'people' becomes 'nation'.
'cor'+'o'+'nation'='CORONATION'
Can you help me to learn more?
(Other definitions for coronation that I've seen before include "Enthronement" , "street?" , "Royal ceremony of 1953" , "Ceremony of installing a monarch" , "Crowning" .)