Individual, defending head coroner, finished quick examination (8)

'quick examination' is the definition.
I don't know anything about this answer so I can't judge whether this works.

'individual defending head coroner finished' is the wordplay.
'individual' becomes 'one' (an individual is one person).
'defending' means one lot of letters goes inside another (inserted letters are defended).
'head' says to take the initial letters.
'finished' becomes 'over' (over can mean finished or ended).
The initial letter of 'coroner' is 'c'.
'one' placed around 'c' is 'once'.
'once'+'over'='ONCEOVER'

Can you help me to learn more?