From on the ground at a non-towered airport via direct communications with center (via center frequency or RCO):
Your call: “Kansas City center, Cessna seven zero four golf lima, on the ground at Clinton, request clearance to Kansas City Downtown airport.”
Center: “Cessna seven zero four golf lima, Kansas city center, cleared from the Clinton memorial airport to the Kansas city downtown airport as filed. Climb and maintain 3000, expect 6000 one zero minutes after departure. Departure frequency one two five point three two. Squawk two seven six one. Clearance void if not off by one zero five zero zulu. If not off by one zero five zero zulu advise Kansas city center not later than one one zero zero zulu of intentions.”
From on the ground at a non-towered airport via FSS:
FSS: “Columbia flight service”
You: “This is the pilot of Cessna seven zero eight golf lima, on the ground at Clinton, requesting clearance to Kansas city downtown airport.”
FSS: “Roger, standby one.”
After a few minutes, FSS: “I have your clearance, advise ready to copy”
You: “I am ready”
FSS: “ATC clears November seven zero eight golf lima from the kilo golf lima yankee airport to the kilo mike kilo Charlie airport via as filed. Climb and maintain 3000 feet, expect 6000 feet one zero minutes after departure. On departure contact Kansas city center on one three two point zero two. Squawk five five four six. Clearance void if not off by one zero five zero zulu. If not off by one zero five zero advise Kansas city center not later than one one zero zero zulu of intentions. Time now one zero one six and one quarter.”
After departure from a non-towered airport via direct communications with center:
Your call: “Kansas city center, Cessna seven zero eight golf lima, airborne off Clinton, requesting IFR clearance to Kansas City downtown airport.”
Center: “Cessna seven zero eight golf lima, Kansas city center, squawk two one six four.”
You: “Squawk two one six four, Cessna seven zero eight golf lima.”
Center: “Cessna seven zero eight golf lima, radar contact eight miles northwest of clinton airport, verify leaving two thousand eight hundred.”
You: “Cessna seven zero eight gold lima, affirmative.”
Center: “Cessna seven zero eight golf lima cleared to the Kansas City Downtown airport via direct, climb and maintain 6000.”
Reference: FAR 91.173
Reference: Instrument Flying Handbook Appendix A-1: Clearance Shorthand
Reference: AIM 4-4-1: A clearance is "not authorization for a pilot to deviate from any rule, regulation, or minimum altitude nor to conduct unsafe operation of the aircraft."