Old woman leaves the Mystery Cat in hollow (6)
I believe the answer is:
cavity
'hollow' is the definition.
(I know that cavity is a type of hollow)
'old woman leaves the mystery cat' is the wordplay.
I cannot really understand how this works, but
'woman' could be 'vi' (short for Violet) and 'vi' is present in the answer.
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is found in the answer.
The remaining letters 'cay' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
'in' is the link.
Can you help me to learn more?
(Other definitions for cavity that I've seen before include "A hollow within a solid, say tooth" , "Destination for a filling!" , "Hole, gap" , "Hole, crater" , "A hole could mean work for the dentist" .)