Knotty old dear? (6)
I believe the answer is:
granny
'knotty old dear?' is the definition.
The answer and definition can be both people as well as being singular nouns.
Perhaps there's an association between them I don't understand?
This is the entire clue.
Can you help me to learn more?
(Other definitions for granny that I've seen before include "Elderly relative's attempt at tying string?" , "one possibly given a flat?" , "Mother's mother, say" , "Sort of knot" , "Insecure knot" .)