Crossword Genius

Figure a girl associate with singing boatmen (5)

Ross

I believe the answer is:

volga

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

'associate with singing boatmen' is the definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.

'figure a girl' is the wordplay.
'figure' becomes 'v' (I can't justify this - if you can you should believe this answer much more).
'a girl' becomes 'Olga'.
'v'+'olga'='VOLGA'

Can you help me to learn more?

(Other definitions for volga that I've seen before include "Major River in Russia" , "runner abroad" , "Europe's longest river" , "Major Russian river" , "River flowing into the Caspian Sea" .)

I've seen this clue in the Evening Standard.
Want a hint initially instead of a full solution? Install my app