Is it normal for a 5yo to develop a clearing throat tic, what should I do about this?

It's typical. 5 yr olds develop transient tics of this sort quite frequently. Best to ignore them.
Common. Various tics occur frequently in childhood. The best initial approach is to monitor. Also, throat clearing tics often occur in kids who struggle with allergies, so it is good to evaluate for allergies and treat if needed.