What's a relatively simple image that could be used as an icon to symbolize "Relevance", such as Search Relevance?

I really can't think of anything that would be instantly recognizable, or even that a user might guess was the thing they were looking for. The best I've come up with so far is a magnifying glass with some other symbol inside:

* A symbol indicating relevance score, like a percentage (%) sign
* A symbol indicating relevance weight, such as balancing scales or a literal weight
* A symbol indicating intelligence or learning, such as a graduation cap or light bulb

But I don't like any of these because combining 2+ objects makes icons look clumsy, and more importantly, none of them seem to immediately convey the purpose of the icon.

Anyone have a better idea?

**Edit:**

1. I'm looking for a single icon to represent the concept. Users will click the icon to re-sort a list of search results according to search relevance (e.g., instead of alphabetical or by date).
2. The context is a web-based application serving users in professional service industries (legal, financial, academic, etc.) so it's got to be clean and professional looking.