Keyhole operation (5)
I believe the answer is:
event
'keyhole operation' is the definition.
The answer and definition can be both acts as well as being singular nouns.
Perhaps there's a link between them I don't understand?
This is the entire clue.
Can you help me to learn more?
(Other definitions for event that I've seen before include "A noteworthy happening or occurrence" , "Something that happens - part of a programme?" , "Something taking place" , "Something happening" , "Planned public or social occasion" .)