Challenge, face (8)
I believe the answer is:
confront
I believe this clue is a double definition.
'challenge' is the first definition.
(I've seen this before)
'face' is the second definition.
(I know that face can be written as confront)
(Other definitions for confront that I've seen before include "Face in opposition" , "Face up to (a problem)" , "Square up to" , "Accost, come face to face with" , "Meet face to face with" .)