Did you perhaps mean "lion’s share?, i.e. most? Lions do not have lairs, they have dens. I know, I was a Cub Scout.
Yes, I have heard the expression “lion’s share” but not “lion’s lair”.
@chipgreen @davirom https://www.theguardian.com/education/2014/jun/09/guide-to-cockney-rhyming-slang