Idiom meaning diverting somebody's attention from a topic which you don't want to talk on
Solution 1:
change the subject
This is indeed an idiom in its own right.
e.g.
I can't get any straight answers from you if you keep changing the subject.
Solution 2:
I hear this given as the process of deflecting:
deflect v
To turn aside or cause to turn aside; bend or deviate.
TFD
Solution 3:
Pivoting or dodging the question comes to mind based on how I would describe politicians.