Green’s Dictionary of Slang

1. resourceful, cunning; also as adv.

1839		W.A. Miles Poverty, Mendicity and Crime; Report 168: Cocum gonnofs flash by night the cooters in the boozing kens, and send their lushy shicksters out to bring the ruin in.
1846		Swell’s Night Guide 40: The French shicksters fight coakum better than our shakes; they do not lush nor scrap, and can sweeten a swell better.
1857		‘Ducange Anglicus’ Vulgar Tongue 9: cocum — very cunning and sly.
1864, 1867, 1870		Hotten Sl. Dict.
1882		Sydney Sl. Dict. 9/2: Kino’s cocum, and he’s stagging to crack the crib. [...] Kino’s wary, and he is watching to break into the house.
c.1886		‘The Flippity Flop Young Man’ [broadside ballad] A know pretty-well-what-is-kocum young man When addressing a constituency [F&H].
1895		Crowe Aus. Sl. Dict. 28: Cocom, cunning or sly.

2. sensible.

1861		Earl Ups and Downs of Aus. Life 224: No one was to get drunk, the governor said as to how it wasn’t cokum, and he woudn’t have it .
1865		Leaves from Diary of Celebrated Burglar 41/1: It wouldn’t be ‘cokum’ for me to go, for the ‘bloke’ has already ‘grannied my mug’.
1900		Sporting Times 20 Jan. 1/5: Tired? [...] Gorblimy, I’m done to the world, and yet it’s ’ardly cocum to—er—stop for arrest, eh?

3. sorted out; arranged satisfactorily.

1865		Leaves from Diary of Celebrated Burglar 90/2: We then finished the bottle, and walked to the bar where, on ‘squaring up’ with Ned, he said he hoped all was ‘cocum’.
1895		E. Powel [perf. Charles Coborn] ‘Four Fingers and a Thumb’ 🎵 But he doesn't think it cokum when it comes to picking oakum / With his four pilf'ring fingers and a thumb.