Hello,
Force definitions to SEP clients could be done by -
1) Right click on the Group / Client within the Group and Click on "Run Command on Group" and Click on "Update Content".
2) Under client Computer, Start > Run > Type 'smc -updateconfig' (without quotes) and click OK
3) Opne the SEP client > Click on Help > Troubleshooting > Click on "Update Policy".
4) Right click on the SEP client ICON on the Task Bar and Click on "Update Policy"
NOTE: All the above points would work on simple condition - the clients should be communicating to the SEPM properly.
Hope that helps!!