Green’s Dictionary of Slang

1. natural intelligence, instinctive knowledge, esp. as used in petty crime or other marginal occupations.

1979		New Musical Express 17 Nov. n.p.: ’Cos there’s such a thing as Mod Suss – you know – sussing out a situation. That’s what Mods are about – suss out a situation immediately, its potential, controlling it. [...] Without his style, his ‘suss’, it’s doubtful whether The Who would carry the cultural weight they do today.
2000		Hip-Hop Connection Jan./Feb. 45: His combination of skills, self belief and raw hustler suss.

2. a piece of information.

2004

P. Howard PS, I Scored the Bridesmaids 63: Hennessy phones the old man from New York, tells him the whole suss.