If you are referring to a nose (as in the nose on your face) you can
just tap your nose twice with the tip of your index finger. If
you are referring to the nose of an airplane then use a classifier
showing the cone shape. If you are using "nose" to mean the front of
a thing then use the sign "front."
You can learn
American Sign Language (ASL) online at American Sign Language University ™
ASL resources by Lifeprint.com © Dr. William Vicars