Crossword Genius

We hear the officers are surrounded by shells! (7)

Ross

I believe the answer is:

kernels

I'm a little stuck... Click here to teach me more about this clue!

'shells' is the definition.
The answer and definition can be both plants as well as being plural nouns.
Maybe there's an association between them I don't understand?

I cannot understand how the rest of the clue works.

Can you help me to learn more?

(Another definition for kernels that I've seen is " Centre parts of nuts".)

I've seen this clue in The Irish Independent.
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