Dangerous Lady by Martina Cole

No one thinks a 17-year-old girl can take on the hard men of London's gangland, but it's a mistake to underestimate Maura Ryan: she's tough, clever and beautiful - and she's determined not to be hurt again, which makes her one very dangerous lady.  Ducking and diving is a way of life down Lancaster Road; all the Ryans are at it. But Michael, the eldest, has ambitions beyond petty crime. His little sister, Maura, turns a blind eye to his misdeeds until they cost her the only man she’s ever cared about and she decides to join the family “firm”.

Reuploaded Thanks to arden