A river journey for ancient boat with many oarsmen (4)

I believe the answer is:

argo

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'ancient boat with many oarsmen' is the definition.
I can't tell whether this definition defines the answer.

'a river journey' is the wordplay.
'river' becomes 'r' (abbreviation for river).
'journey' becomes 'go' (I've seen this in other clues).
'a'+'r'+'go'='ARGO'

'for' is the link.

Can you help me to learn more?

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

I've seen this clue in The Guardian.

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