Green’s Dictionary of Slang

1. worked out.

1970		‘Metropolitan Police Sl.’ in P. Laurie Scotland Yard (1972) 328: sussed out, to be: to have one’s disguise or hiding-place penetrated.
1984		Newcastle Jrnl 6 Dec. 8/7: [He] is alleged to have told police he ‘had it all sussed out’.
1998		I. Welsh Filth 158: These Dutch cunts have got it sussed. [Ibid.] 314: That English cunt Dolacre, he’s got us daft Jocks well sussed out.
2003		Sun. LIfe (NI) 23 Mar. 103/7: For Meath star has Clarke’s injury sussed out.

2. clever, sophisticated, aware.

1989		J. Hibberd Memoirs of an Old Bastard 87: The Adelaide bore [...] espousing the causes of the modern woman, insisted that the grant would ‘not be suss’ as long as the donkey were female.
1998		A. Warner Sopranos 199: The sisters, they’re all so dottery [...] at least Mr Eldon’s a bit sussed.
1999		Indep. Rev. 3 Nov. 8: Looking as cool and sussed as Bryan Ferry.
2000		Guardian Guide 15–21 Jan. 29: You’re crying out for somewhere with a sussed music policy.
2000		Guardian Guide 26 Feb.–3 Mar. 11: She’s very bright and very sussed.

3. (UK Und.) arrested.

1977

D. Powis Signs of Crime 203: Sussed Arrested as a suspected person loitering.