Open WSUS manager, expand the server and select Options.
Click Products and Classification
Select Windows Defender and click Apply
Click the Classifications tab, select Definition Updates and click OK
Click Automatic Approvals and then New Rule
Select When an update is in a specific classification and then lower click the link any classification
Unselect all except Definition updates and click OK
Then click all computers link.
Select only the computers you want to receive the updates and click OK. Then on the third step choose a name for the rule and click OK
Click OK again and you are done!