Increase keenness (5)
'increase keenness' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how one could define the other.
This is all the clue.
Can you help me to learn more?
(Other definitions for strop that I've seen before include "Fit of bad temper" , "Razor sharpener" , "Display of temper" , "Leather strap used to sharpen razors" , "rage" .)
'increase' is the definition.
(I know that sharpen is a more specific form of the action deepen)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for sharpen that I've seen before include "Make pointed" , "Raise pitch of" , "Restore edge to knife" , "instrument secured by former nurse" , "Get keen" .)