1
general::
Phrase(s): hang back (from someone or something)
to lag back behind someone or something; to stay back from someone or something, perhaps in avoidance. • Why are you hanging back from the rest of the group? • Come on! Don’t hang back!
McGrawhill's American Idioms And Phrasal Verbs
2
general::
Be reluctant to move ahead, hold back. For example, They hung back at the entrance, fearful that they wouldn't be admitted, or We hung back to let our parents go in first. [Second half of 1500s]
American Heritage Idioms