Bony vegetable? (6)

I believe the answer is:

marrow

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'vegetable?' is the definition.
(marrow is a kind of vegetable)

I can't explain the remainder of the clue.

(Other definitions for marrow that I've seen before include "Vegetable - tissue in bone" , "Large green squash" , "Oversized courgette" , "Edible gourd" , "Soft tissue in bones" .)

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