Was upset as queen left German jumbuck stealer (7)

I believe the answer is:

swagman

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

'queen left german jumbuck stealer' is the definition.
The definition suggests a singular noun which matches the answer.

'was upset as' is the wordplay.
'upset' is an anagram indicator.
'as' becomes 'gman' (I am not sure about this - if you are sure you should believe this answer much more).
'was' anagrammed gives 'swa'.
'swa'+'gman'='SWAGMAN'

Can you help me to learn more?

(Other definitions for swagman that I've seen before include "Aussie worker" , "Drifter" , "itinerary" , "Australian tramp" .)

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

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.