Perfect! Is there a way that I could have the approval field reset itself to "pending" if it was approved by someone other than the required user?

It would be slightly more complicated, but yes, you could.

Wait for Entry Change produces tokens with the name of the user who made the change, but those are only available once the activity completes. So we need to change what we're waiting on a bit.

So instead of waiting for the field to be set to "approved" by a specific user, we're just waiting on it to no longer be "pending". Then evaluate who made the change and set it back to "pending" if the user is not the right one. That's the Wait For Entry Change plus Conditional Sequence above.

The problem you have then is that if the wrong user made the change, you still want to wait for the right one, except that now you're outside the wait activity. That's where Repeat comes in. If the status field is still "pending", Workflow will go back into "wait and check who did the work" steps.