I just erased a contact mistakenly. How do I get it back? My last iCloud backup was yesterday

No need to use the iCloud backup. You can restore only your contacts by:

• On iCloud.com, go to Account Settings, then click Restore Contacts in the Advanced section. Available versions are listed by the date and time they were archived.
• To the right of the version you want to restore, click Restore. There may be more versions than can be displayed. Scroll to see them all.

Note: Wait until iCloud finishes restoring your contacts before you change them. During the restore process, any changes you make aren’t saved.