the shortest clue in cryptogram history:
e (13 letters)

I think you are referring to Cryptic Crosswords, full of all kinds of wordplay, rather than cryptograms, subtitution-coded phrases.

If that's your cup of tea, drop in on the NPL (National Puzzlers' League) site at http://www.puzzlers.org and sample what they have to offer.

They pride themselves in their cleverness and word-savvy, and perhaps justifiaby so. And they have come up with bunches of phrases that they have expressed cryptically as a single letter !

P.S. "senselessness" ? No, that would apply to any nonsense collection. I'll work on it some more.