keep back

verb4

1. •
   To stay back; to refrain from approaching.
2. •
   To restrict or restrain.

   • Germany eased off in the second half and this was a night when Joachim Löw, like Southgate, took the opportunity to keep back his best XI. — 2017
3. •
   To prevent (a pupil) from advancing in a course.
4. •
   To hold back; to refuse to give or share.