^^ Easiest method.
Quick FYI - a clip is a "window" into the underlying audio file, so the above will make it "visually" different but not change the underlying audio file in any way. In order to change that (just in case audio size is another intent), you would need to do a "Save As.." and check "Create one file per clip."
I have never used that setting, but SONAR records to disk straight from the interface so would only recognize "gaps" after enough time has passed, but the "silence" is actually necessary to maintain timing when only one wav file is involved (which is the case with tracking).