Determination, resolve (4)
I believe the answer is:
grit
This clue is a double definition.
'determination' is the first definition.
(grit can mean determination or tenacity)
'resolve' is the second definition.
(I've seen this in another clue)
(Other definitions for grit that I've seen before include "Bottle" , "called for on icy roads" , "Determination -- coarse sandstone" , "Coarse stone or sand" , "Courage, determination" .)