Green’s Dictionary of Slang

alert, aware, ‘no fool’.

1840		Flash Mirror 20: J. Maggot [...] pounces on this opportunity to put his pals wido that he has opened a swell ‘Buttick’ for caso, alias a rummy beeswax warehouse.
1842		Bell’s Penny Dispatch 17 Apr. 4/2: ‘Pals be d—d [...] he’s only dropt in with crossmen a little more wide’o than himself’.
1844		New Sprees of London 3: Nanty palary the rumcull of the Casey is [...] quisby in the nut, not fly, not up to the moves, not down to the dodges, not awake, can't tumble to the slums, not wido to the slangs.
1854		F. Smedley Harry Coverdale’s Courtship 165: He’s so ‘wide-o,’ that it’s not so easy to nab the warmint.
1862		J.A. Hardwick ‘The London Scamp’ in Prince of Wales’ Own Song Book 50: Living reckless, gay, and free, [...] Reckoning up society / Like a wido London scamp – A regular downy London scamp.