Its a simile, basically hes suggesting by holding onto anger, you’re just waiting until you act on it by taking it out on someone
"and don't be afraid if not""stick close to me""well cut him to fit the clothes I gave you something for your soul"
Todd is reluctant to join the Dead Poets' Society because he doesn't like reading aloud. He doesn't feel comfortable doing that which is why he is hesitant to join the club. However, Neil helps him by telling him he should just come and join them, and he doesn't have to read until he is ready to do so.
I would say B. gerund phrase. I just learned about this a week ago
