Theoretically yes, practically, no, and certainly not if LF are asking during startup. The problem is that if a clearance is issued, TC then have to provide separation from 'the clearance' not 'the plane'. For example, if you were cleared to join on track Goodwood climbing to 5000 say, (although that would leave CAS again if not climbed, but that's another matter) then KK SAM and KENET departures would have to be stopped as they are not separated from LF climbing to 5000 to GWC. Now why do we treat KK as more important than LF you may ask. Well, we don't, it's just that with the relative traffic volumes generated, it's easier and better for the overall traffic flow if you give a remain outside to the quiter places rather than stopping traffic from the busier ones. This is however changing somewhat as certain traditionally smaller quiter airfields expand.
Who knows what the future holds.