With which the timorous may approach the settlement (11)
I believe the answer is:
reservation
'settlement' is the definition.
The answer and definition can be both acts as well as being singular nouns.
Perhaps you can see an association between them that I can't see?
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for reservation that I've seen before include "Putting aside" , "Expression of doubt (about a claim)" , "Qualification, proviso" , "Expression of doubt; table booking" , "Booking - qualification" .)