Arglists of some functions are quite long and they may not fit on the screen in one line, there are two ways to display them.
(setq slime-autodoc-use-multiline-p t)
that’ll make the minbuffer change its height automatically to accommodate several lines of text.
But I find it annoying when the minibuffer jumps up and down, especially when I don’t really want to read the whole arglist.
For this case there’s a binding C-c C-d A (not an easy one), it will redisplay the current arglist on several lines. And its effect is temporary.
You can try it on WRITE function