Elusive cat mum lost in pit (6)
I believe the answer is:
cavity
'pit' is the definition.
(I know that pit can be written as cavity)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for cavity that I've seen before include "Destination for a filling!" , "Hollow place" , "Hollow space" , "A hole could mean work for the dentist" , "Decayed part of tooth" .)