At the High Court yesterday Mr Hancock issued a public apology to a vulnerable woman constituent for making inappropriate sexual advances after she sought his help as her local MP and councillor.
Speaking on his weekly LBC radio phone-in, Mr Clegg said the MP for Portsmouth South - who has already had the LibDem whip withdrawn in Parliament and his party membership suspended - should now leave the party altogether.
"He should resign from the party. Of course he should. Absolutely," Mr Clegg said.
Mr Clegg was forced to defend his failure to act sooner after the woman, who suffers from mental health problems, complained that the LibDem leader "turned a blind eye" after she contacted his office asking the party to investigate.
She told a newspaper: "Clegg has been negligent, he has put me through hell. I complained to Clegg's office in March 2011, but it has taken four years to deal with Hancock. There is supposed to be system in place in the party to deal with MPs but they don't seem to use it."
Mr Clegg acknowledged that a letter had been sent to LibDem headquarters in 2011, but said it had never been brought to his attention.
He said the party had taken no action at that time as Hampshire Police and the Crown Prosecution Service, which had both looked into the matter, had decided there was no basis on which to proceed.
"She is quite right to say back in 2011 something was sent to my office. It didn't reach me," he said.
"When I was given specific allegations early in 2013, Mike Hancock was suspended as an MP for the party."