Yes axanthic clown is more difficult as you are dealing with 2 separate recessive genes, so both parents must have at least 1 copy of each (i.e. be double hets at least) visual for one, het for the other and vice versa would be better. For a black pastel clown only 1 parent needs to carry the BP gene, although both need to carry clown.
so clown x axanthic = het clown , then breed them back together? or is there more haha