The Oracle of Stone's Clobbering Strike Revelation allows him to make an automatic trip attempt anytime he hits with a spell that requires an attack roll. I presume that means spells where you make an attack roll when you cast the spell, and not attacks with a weapon granted by a spell, such as Magic Stone? What about Spiritual Weapon, which creates a weapon which attacks on its own as part of the spell?
Firstly: its only when she crits "with a spell that requires an attack roll"
There are a few spells that require an attack roll. Spiritual weapon certainly is one of them. If the weapon crits, there will be a free trip attempt.
This is quite a weak revelation tbh but it works with spiritual weapon which makes it less horrible.