I need help relearning!

So I play clarinet, well, to be specific, I did a long time ago. I was asked by my old theatre teacher to join in the pit for this school years upcoming production of Something Rotten. Anyway, I started in '03, and quit playing in '13. So it's been over a decade since I last picked up my instrument in a serious way. What exercise suggestions do you all have for me in terms of getting back into the swing of things. Any source materials y'all know that would help? I really want to do this, but I don't want to let him (or myself) down.