Whet (7)
I believe the answer is:
sharpen
'whet' is the definition.
(I know that whet is a is a more specific form of the action sharpen)
This is all the clue.
(Other definitions for sharpen that I've seen before include "instrument secured by former nurse" , "Put a point on" , "Whet" , "Raise pitch of" , "Hone (a knife blade)" .)