crontab run every minute after 9pm

Question

I want the command to run every minute after 9pm. What should I do?

For testing, below schedule is not working.

1. not working

   */1 21 * * * date >> /opt/cron.log 2>&1

2. working

   */1 * * * * daet >> /opt/cron.log 2>&1

I want the command to run every minute after 9pm.