The clue with the Ls makes no sense. Iamb does not contain an L to replace, and IAN is a name and should not be included in a word clue like this

Only 1 word from the replace line is actually a word...waist, Isan, Isamb and Tois are not words I am familiar with, but even if they are words, too obscure for guessing. 3 of your Mountain chains are already referred to in the singular, so the clue is redundant, and the 4th doesn't work because Andy is not singular for Andies. American Pie line has references that could genuinely be from anything..nothing specifically ties them to the clue, so no chance of guessing, and Ark and Arc are 2 entirely separate things, so there is no way you can bundle them together just because they sound similar. Not being picky for the sake of it I promise...just constructive criticism. :)

Ok , so just realised you meant I's not Is......still stand by the other points

asdf......Lamb doesn't have an L to replace??