Yonder state's girl (7)

I believe the answer is:

theresa

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

'girl' is the definition.

'yonder state's' is the wordplay.
'yonder' becomes 'there' (I've seen this before).
'state' becomes 'sa' (I am not sure about this - if you are sure you should believe this answer much more).
'there'+'sa'='THERESA'

Can you help me to learn more?

(Other definitions for theresa that I've seen before include "Maria -, Austr. empress" , "Maria ___ , Archduchess of Austria, d. 1780" , "-- May, MP" , "May's one" , "Lisieux saint" .)

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

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