Legendary ship's captain abandoned cargo (4)

I believe the answer is:

argo

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

'legendary ship's' is the definition.
(ship in Greek myth)

'captain abandoned cargo' is the wordplay.
'ARGO' is hidden within the letters.
However, I'm unsure how this is indicated.

Can you help me to learn more?

(Other definitions for argo that I've seen before include "Fabulous ship" , "Jason's craft" , "Ship Jason sailed to find the Golden Fleece" , "Old boat" , "Mythical ship" .)

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

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