Crossword Genius

Pulse started with heart bypass (4)

Ross

I believe the answer is:

bean

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'pulse' is the definition.
(beans are a type of pulse)

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

Can you help me to learn more?

(Other definitions for bean that I've seen before include "See 12 Down" , "comic character" , "Vegetable, could be green or broad" , "coffee, perhaps" , "Plant with seed in pod" .)

I've seen this clue in The Sun.
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