Despite confusion by the media, there is a significant difference between "covert" operations and "clandestine" operations.
Covert operations: operation should be undetected while in progress, but the outcome may be easily observed. Example: special operations team secretly inserted behind enemy lines to destroy a high-value target.
Clandestine operations: operation should be undetected while in progress and after completion. Example: steal copies of enemy intelligence reports.
In both cases the identity/ties of the operators may be kept hidden or disguised after the operation is complete.