as autumn descends
a spider claims the darkest
corner by the stove
Again, there are two season words—“autumn descends” and “spider”—but there is no confusion about which is the focus of the poem. This is classical haiku of seasonal transition.
The spider (a creature of summer and therefore a summer word, even though it can be found in other seasons) has chosen a dark place to live out its remaining days. The mood is somewhat sad and autumnal, but the focus of the poem is on the inevitability and naturalness of the descending autumn. This is the season of leave-takings, and the spider conveys that perfectly, making it the perfect secondary season word for a poem on that theme.
Here is a haiku by Soen Nakagawa Roshi that expresses a similar idea, although the season, being springtime, establishes a very different mood:
the place established
for the bagworm is among
the cherry blossoms