Grasp the nettle (4,3,6)
I believe the answer is:
bite the bullet
'grasp the nettle' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for bite the bullet that I've seen before include "resign oneself?" , "Grapple with a problem head on" , "Commit oneself" , "Be stoical" , "Face the music" .)