What's a good example of a kenning in Beowulf?

A kenning was simply a compound metaphor of two or more words. In theory, kennings can be multiple words, but in practice, they were usually two or sometimes three word combinations. The poem is replete with examples. Beowulf's name itself is a riddle in the form of a kenning: Beo=Bee+wulf=wolf (the wolf of bees, i.e. a bear)

Kings are called ring givers, swords are called battle gleams, the sea is called the whale road or the swan road, the sun is called sky candle and heaven's joy.

There are literally hundreds of examples.