Ambiguous, use Hand On Own Arm or Grabbing Another'S Arm.
See also
- Arm Hug (using both arms to surround another's arm)
- Holding Another'S Arm
- Hand On Own Arm
- Holding Another'S Wrist
- Locked Arms (inner elbows touching)
- Arm Held Back (a type of Grabbing Another'S Arm)