An ending to a meal - or it could be a preamble (4,5)

I believe the answer is:

pear melba

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'an ending to a meal' is the definition.
I know nothing about this answer so I cannot tell whether it can be defined by this definition.

'it could be a preamble' is the wordplay.
'it could be' indicates anagramming the letters (I've seen this in other clues).
'a'+'preamble'='apreamble'
'apreamble' with letters rearranged gives 'PEAR MELBA'.

'or' acts as a link.

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