Plain English Meaning
The controller you call before you start moving to get permission for your flight, including your route, altitude, and any special instructions. CLNC DEL is just the short form of that controller's name and the frequency you use to talk to them.
Full Definition
An air traffic control position, and the associated radio frequency, responsible for issuing IFR clearances (and certain VFR clearances) to departing aircraft before taxi. On instrument approach charts and airport diagrams, CLNC DEL appears in the communications strip alongside the frequency a uses to request and receive their .