Shame about test essay hampering smooth opening (13)

I believe the answer is:

sandpapergate

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'shame about test essay hampering' is the definition.
I know nothing about this answer so I can't judge whether this works.

'smooth opening' is the wordplay.
'smooth' becomes 'sandpaper' (to smooth with sandpaper).
'opening' becomes 'gate' (a gate is an opening or entrance).
'sandpaper'+'gate'='SANDPAPERGATE'

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

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