Watch a big bee dismember a butterfly (7,5)

I believe the answer is:

cabbage white

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

'butterfly' is the definition.
(I've seen this before)

'watch a big bee dismember a' is the wordplay.
'watch a big bee' can be anagrammed to 'CABBAGE WHITE'.
But, I am not sure how this is indicated.

Can you help me to learn more?

(Other definitions for cabbage white that I've seen before include "insect" , "Common pest butterfly" , "summer visitor" , "Common British butterfly" , "We bag ice bath (anag) - butterfly" .)

I've seen this clue in The Irish Independent.

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