Relatively insecure sort of fastening? (6,4)
I believe the answer is:
granny knot
This might be a double definition.
'relatively insecure sort' is the first definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.
'fastening?' is the second definition.
(granny knot is a kind of fastening)
'of' is the link.
Can you help me to learn more?
(Other definitions for granny knot that I've seen before include "Rope fastening" , "Elderly relative's attempt at tying string?" , "Something tied but liable to slip" , "Bad connection between lines" , "Result of not tying a reef properly" .)