Does anybody know if you can cover a lemon sponge cake in fondant? will it hold up very well?

It will really depend on the recipe to be honest! If it's a dense cake, then it shoudl be fine, but if it's a very light cake it may not take too well to it. Lemon cakes can be made using hundreds of different recipes, which all produce a different cake texture. HTH!

thanks!

What u can do, if you think your cake nay not be dense enough, i.e if it's a pretty light cake, is lightly ice it smooth, let that layer dry, and then apply your fondant. the icing layer should hold everything together. Btw, does your fondant dry a bit stiff or does it remain soft?