Das scheint im Großen und Ganzen in Richtung (des oben schon erwähnten) Siehe Wörterbuch: hobo zu gehen :
Derived from the word 'derelict'. Means an unkept person.
Used in a sentence
Get a job you bloody derro! ...
Meaning of 'Derro'
A homeless person. Derived from 'derelict'. Also used more broadly to non-homeless people exhibiting classic homeless markers: shabbily dressed, very poor, smelly.
Example of 'Derro'
Shazza brought a bloke back last night. Not the usual derro, either. This fella had his own place and a job even!
Also spelled ‘Dero’. ...
... Cusack says he did not set out to make a statement about a certain type of man he describes as "part derro, part yobbo, part bogan". He says Damo and Darren were "subconscious influences from going to Woolies to get milk and bread and waiting in line and observing". ...
... After interval at a hotel in the city the return journey sees the return of the old derro (who had been chucked off the tram on the way in by the punk) as well as the return of the bickering couple and the socialite who has just confronted her husband in the foyer of the Melbourne Theatre Company. As matters reach a climax the derro attempts to hijack the tram after an altercation with the ticket inspector who staggers off into the night thinking he's stabbed the old man (but only hit his pie and tomato sauce). ...