Leigh Griffiths of letting down Neil Lennon with his lack of professionalism in lockdown.Hitman Griffiths has been left behind at Lennoxtown to work on his fitness while the squad head to France to take on Lyon, Nice and PSG in friendlies.Boss Lennon is understood to be furious with the frontman’s condition and has ordered him to get up to speed at home.Parkhead legend Sutton has hailed Griffiths for overcoming his issues in the past to play a starring role in the title run-in last term.But he