Key in pharaoh's lock (4)
I believe the answer is:
tuft
'key in pharaoh's lock' is the definition.
Although both the answer and definition are singular nouns, I can't see how they can define each other.
'key in pharaoh's' is the wordplay.
'key' becomes 'f' (I've seen this in other clues).
'in' is an insertion indicator.
'pharaoh' becomes 'tut' (colloquial name for Tutankhamun).
'f' going into 'tut' is 'TUFT'.
Can you help me to learn more?
(Other definitions for tuft that I've seen before include "Bunch of hairs" , "Dog's lead" , "Cluster of hair, grass etc" , "Wisp" , "Bunch of threads or hair" .)