I've tried XWordinfo.com and the problem is that it's like trying to prove that unicorns don't exist because there are none in your sock drawer. In other words, it's easier to prove something DOES exist than that something DOESN'T exist. I've been poking around at it seems that my best option is to just clue my partial as a "Lead-In."
What might still be interesting is any advice on how to search for something like this in a clue db. The best I could come up with was to do a search for "lead-in" and to pick a frequently used partial compound word and the to see how else THAT word was clued. I landed on "micro" on Xwordinfo and didn't find any FITB clues. By no means conclusive, but is there even a better way?