Something crusty-looking extracted from mollusc, absentmindedly (4)

I believe the answer is:

scab

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'something crusty-looking extracted' is the definition.
I can't judge whether this definition defines the answer.

'from mollusc absentmindedly' is the wordplay.
'from' says the answer is hidden in the clue.
'SCAB' is hidden in the letters of 'mollusc absentmindedly'.

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(Other definitions for scab that I've seen before include "Strikebreaker; mange" , "Wound's crust" , "Scoundrel" , "cover" , "Crusted sore on cut or wound" .)

I've seen this clue in The Irish Times.

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