Tailless fish rolled in seed, nuts and cooked in breadcrumbs (10)

I believe the answer is:

escalloped

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'cooked in breadcrumbs' is the definition.
The definition suggests a past participle verb which matches the answer.

I don't understand how the remainder of the clue works.

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(Another definition for escalloped that I've seen is " covered in shells".)

I've seen this clue in The Guardian.

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