Crop old man’s yabbies (8)

I believe the answer is:

crawdads

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'yabbies' is the definition.
I can't tell whether this definition defines the answer.

'crop old man's' is the wordplay.
'crop' becomes 'craw' (synonyms).
'old man's' becomes 'dad's' (both can mean one's father).
'craw'+'dads'='CRAWDADS'

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

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