Student's assessment of author Alexa Martin's piece (4,4)

I believe the answer is:

oral exam

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'student's assessment' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.

'author alexa martin's piece' is the wordplay.
'piece' indicates the answer is hidden within the clue.
'ORAL EXAM' can be found hidden inside 'author alexa martins'.

'of' acts as a link.

Can you help me to learn more?

(Another definition for oral exam that I've seen is " Viva voce test".)

I've seen this clue in the Sydney Morning Herald.

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