Green’s Dictionary of Slang

(Aus.) a rest, a holiday; also as v.

1893		H. Lawson ‘Bill, the Ventriloquial Rooster’ in Roderick (1972) 142: Bill had come home tired; it was a hot day [...] and was having a spell-oh under a cask.
1898		E. Dyson ‘A Zealot in Labour’ in Below and On Top 🌐 You can spell-oh till you pick up a bit, an’ then you can get down to graft.
1902		‘Dads Wayback’ in Sun. Times (Sydney ) 28 Sept. 5/5: [of school holidays] [K]id-whackin’, as 'is an easy job, five hours er day fer five days in ther week, an' two months spell-oh! every year.
1903		‘Dads Wayback’ in Sun. Times (Sydney) 24 May 1/1: ‘[T]hat there lucerne ain't in no hurry, an’ ’ull bide there till mornin’. Take a spell-o, man’.
1914		Bulletin (Sydney) 23 July 10/1: And then while the band is playing we who’re sick of it, you see, / Will sit down and take a spell-oh and just watch the circus gee!
1918		Kia Ora Coo-ee 15 Aug. 4/3: Of course, ‘spello’ is on the routine card four times daily, which enables the dusky bints to exercise their vocal organs.
1941		Baker Popular Dict. Aus. Sl.
1955		N. Pulliam I Travelled a Lonely Land (1957) 239/2: spello (spell-o, spell-oh) – time out for a smoke or rest.
1965		L. Haylen Big Red 100: The sweat of agony on their brows at ‘spello’.