Looking up the spell Snare would only return the items that have that effect. There are lots of spells that can affect run speed: Snare, Ensnare, Dooming Darkness, Engulfing Darkness are the main ones.
I did not find any caster usable clickies besides ones with Snare though, so
for this purpose looking up Snare would get you all the items you could use.
Enchanter usable clickies, a quick search turned up:
Swollen Fungus Beast Gland Ball of Burlap Yarn Nothing has unlimited charge clickies except Ranger / Druid only items. You will be stuck with non-rechargeable snares that are not easily gotten.