Clegg told BBC One's Andrew Marr Show: "We are going to work out ways in which parents and grandparents who want to help their children and grandchildren buy a property of their own.
"We are going to allow those parents and grandparents to act as a guarantee, if you like, so their youngsters... can take out a deposit and buy a home. It is a pension-from-property scheme."
He said he hoped the idea would make the path to homeownership more affordable and that many "desperate" young people would be able to buy their home sooner because the guarantee would mean they needed a smaller deposit.
The Lib Dems suggested this scheme would help parents with pensions give their children a step up onto the property ladder even if they lacked significant savings.
The BBC reported that around 250,000 people had a pension pot of £40,000, with a lump sum element of around a quarter - £10,000 - which could be used as a guarantee.
They estimated that 5% of those with a suitable lump sum would take advantage of the scheme, meaning 12,500 people could potentially benefit.
A spokesman for the Building Societies Association said: “New ideas to assist first-time buyers to get onto the housing ladder are welcome. The use of elements of a pension pot as a guarantee however raises some particularly meaty questions which need careful consideration.”
Ros Altmann of Saga said: “Surely it makes more sense to try to use some of the value of older generations' homes to help younger people buy a house, rather than using their pensions.
“The value of people's pensions many years' hence is not guaranteed. Most pensions are invested in assets that will rise or fall over time, depending on the markets.
“Secondly, most people will need their pensions to support them in retirement, or perhaps for later life care needs. Thirdly, borrowing against a future pension lump sum would be more expensive than taking the money out of the pension fund and using it directly.”
