Crossword Genius

A pointedly obdurate comparison (2,4,2,5)

Ross

I believe the answer is:

as hard as nails

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'comparison' is the definition.
I know nothing about this answer so I can't tell whether this works.

'a pointedly obdurate' is the wordplay.
I cannot quite understand how this works, but
'a' is present in the answer.
'obdurate' could be 'hard' (I've seen this in another clue) and 'hard' is present in the answer.
This explanation may well be incorrect...

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I've seen this clue in The Irish News and The Globe and Mail.
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