The term “customs clearance” is often used for every kind of customs declaration. Technically correct customs clearance relates to the form of importation and describes the procedure and conclusion /release by the customs authority.
In the case of exports, the term “customs clearance” is to be replaced correctly by the term “export declaration” with final clearance by the customs authorities. Similarly, there are for all other customs procedures specific names instead of customs clearance.
What kind of customs procedure in your particular case is the best for you or will achieve the optimum result can be explained upon request.