I have a workflow question, I need to clear a field on a sales order when an approval button is pressed, is there a way to do that? Or what is the best method to accomplish this?

when it goes to the next step of the approval workflow I would set the field in entry to blank

I need to have it blank before leaving the state as the transition requires it

you can also blank on exit from the current state

A button in a workflow can only execute a transition. It cannot perform other actions