At a clothing store, you might see a sign saying Men's Clothing, and the possessive use of the apostrophe correctly indicates that the clothing is suited towards the group "Men" (i.e. more than one man). If the apostrophe was after the 's', i.e. Mens' Clothing, it would cause someone proficient with grammar to assume that there exists more than one group of pluralized men to whom the clothing is suited (i.e. tall men, fat men, green men).
An ambiguity arises with the phrase Ladies' Clothing. It would seem that this use would conform to the second case above (i.e. as Mens' Clothing). This is because there isn't really a word spelled 'ladie' ('y' usually becomes 'ies' in plural), so Ladie's Clothing would clearly be incorrect.
So my question is how do you refer to the possession of more than one lady, but not to the possession of more than one group of ladies, and thereby avoid the ambiguity caused when using the phrase Ladies' Clothing?