Bug with duck sauce (5)

I believe the answer is:

pesto

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'sauce' is the definition.
(pesto is a type of sauce)

'bug with duck' is the wordplay.
'bug with' becomes 'pest' (I can't explain this - if you can you should give a lot more credence to this answer).
'duck' becomes 'o' (resembles zero - 'duck' in cricket).
'pest'+'o'='PESTO'

Can you help me to learn more?

(Other definitions for pesto that I've seen before include "Pasta sauce mainly of basil and cheese" , "Ligurian food" , "Sauce made of basil and cheese" , "Basil-based sauce" , "Pasta sauce variety" .)

I've seen this clue in the Sydney Morning Herald.

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