1.
If something stirs up dust or stirs up mud in water, it causes it to rise up and move around.
They saw first a cloud of dust and then the car that was stirring it up.
PHRASAL VERB: V n P
2.
If you ~ a particular mood or situation, usually a bad one, you cause it.
As usual, Harriet is trying to ~ trouble...
I thought at first that Jay had been stirring things up.
PHRASAL VERB: V P n (not pron), V n P disapproval