$ sudo apt-get update
$ sudo apt-get install clamav-freshclam 

clamav-freshclam is installed in your system.

Make ensure the clamav-freshclam package were installed using the commands given below,

$ sudo dpkg-query -l | grep clamav-freshclam *

You will get with clamav-freshclam package name, version, architecture and description in a table

clamav-freshclam package basic information: