Be stoical (4,3,6)
I believe the answer is:
bite the bullet
'be stoical' 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 "Be stoical" , "Deal with difficulty" , "Grasp the nettle" , "pinch the round?" , "Grapple with a problem head on" .)