Anxious to show how cutting you can be? (4)
I believe the answer is:
keen
'anxious' is the definition.
(I've seen this before)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for keen that I've seen before include "Eager; dirge" , "Sharp - eager" , "Fervent" , "(Of a blade) sharp" , "Sharp - avid" .)