Green’s Dictionary of Slang

1. (W.I.) an untrustworthy, dissolute person.

1986		R. Hewitt White Talk Black Talk 122: Natty Dread jes’ top rankin’. / De Dread is ranker. / Yeah, seh I said de Dread is ranker. / An de Babylon a-skanker. / De Dread is de rankin’.
1997		N. Barlay Curvy Lovebox 123: Scammers an’ skankers.
2012		(con. 1980s) I. Welsh Skagboys 23: Mama’s [...] sobbing and cursing the skanker that’s stolen his brass heart.

2. (W.I.) someone who dances in a style associated with ska, dub or reggae music.

1999

(con. 1979–80) A. Wheatle Brixton Rock (2004) 139: Skankers [...] showed off their new moves and party pieces.

3. an alcoholic tramp.

1997

N. Barlay Curvy Lovebox 94: Past skankers [...] drawin’ on cider and beer.