The Liberal Democrat leader defended his handling of the situation amid claims nothing was done for three years after the party was notified of the complaints.
The Portsmouth South MP was suspended from the party this week after the leaking of a QC's report into claims, which he denies, of inappropriate behaviour towards a constituent with mental health issues. Mr Hancock resigned the parliamentary party whip last year, but was still a LibDem councillor.
Mr Clegg, who is under fire over the handling of sexual harassment claims against Lord Rennard, said: "When I was given the specific allegations at the beginning of last year I immediately asked our chief whip to investigate. As a result Mike Hancock ceased to be a Lib Dem MP."