Hone, whet (7)
I believe the answer is:
sharpen
This clue is a double definition.
'hone' is the first definition.
(I've seen this before)
'whet' is the second definition.
(I've seen this in another clue)
(Other definitions for sharpen that I've seen before include "Hone (a knife blade)" , "Make pointed" , "instrument secured by former nurse" , "Whet" , "Raise pitch of" .)