Hi Frank,
If it looks like single filaments, it should clean. If it looks not so much like a spiders web but more like an enlargement of a snowflake, you may have problems as this is the stuff that secrets hydroflouric acid which etches the glass. Whichever it is do not dry to "dry" clean it but use a fluid. Alcohol, Rosonol or lens cleaner can work but some suggest something a bit more potent to ensure it is killed.
Kim